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Fat loss

Everything in the library studied for it, medical and holistic together. Within each kind, what was shown to help comes first, strongest evidence first. What was tested and not shown to help stays on the list.

Strong several reviews agree · Moderate one review or consistent trials · Limited one or a few small studies · Untested no study in people, listed with what it rests on

Medication31 Hormone therapy6 Peptides and SARMs3 Supplements35 Practices5 Daily life6 Food and drink9 Diets22 Devices and wearables2 Lab markers2

Medication

LevothyroxineStrong

Weight change when treating hypothyroidism

Shown to lower weight about 1.4 to 2.2 kg after treating hypothyroidism, in overt cases only. Weight did not change in subclinical hypothyroidism.

The numbers and sources

Effect: Across 23 studies, weight changed by -1.39 kg (95% CI -2.56 to -0.23) after levothyroxine restored normal thyroid levels. BMI changed by -0.39 kg/m², fat mass by -0.75 kg and lean mass by -0.95 kg. Weight and BMI fell in overt hypothyroidism but not in subclinical hypothyroidism, where lean mass fell [3]. Across 35 studies, weight fell 2.15 kg in overt hypothyroidism, mostly in the first 3 months, with no change in fat mass and a small fall in lean mass. In subclinical hypothyroidism, BMI, weight, fat mass and lean mass did not change [4].
Population: 763 adults with hypothyroidism [3]; 1,116 adults, 672 with overt and 444 with subclinical hypothyroidism [4].
Sources: [3], [4]
Caveats: Both reviews pooled measurements taken before and after treatment, without an untreated comparison group. They disagree on fat mass [3][4].

LiraglutideStrongVery common

Weight loss

Shown to cut about 5.6 kg more weight than placebo over a year in adults with obesity, alongside diet and activity counseling. Adolescents also lost more.

The numbers and sources

How common: Very common: more than 1 in 10 people.
Effect: At 56 weeks, people on liraglutide lost a mean 8.4 kg and people on placebo 2.8 kg, a difference of -5.6 kg (95% CI -6.0 to -5.1). A loss of at least 5% occurred in 63.2% on liraglutide and 27.1% on placebo, and a loss of more than 10% in 33.1% and 10.6% [1]. Across trials of 1 year or more, liraglutide produced 5.3 kg (95% CrI 4.52 to 6.06) more weight loss than placebo [2]. A second network meta-analysis found GLP-1 receptor agonists as a class lowered body weight by 5.79 percentage points (95% CI 5.25 to 6.34) more than lifestyle change alone [3]. In adolescents, body weight fell 5.01 percentage points more than on placebo at 56 weeks [4].
Population: 3,731 adults without diabetes, mean BMI 38.3, 78.5% women [1]; 28 RCTs with 29,018 adults [2]; 132 RCTs with 48,209 adults [3]; 251 adolescents aged 12 to 17 with obesity [4].
Sources: [1], [2], [3], [4]
Caveats: All trials paired the drug with diet and activity counseling. [1] and [4] were funded by Novo Nordisk, the maker. Attrition in the pooled trials ran 30 to 45% [2]. [3] pools all GLP-1 receptor agonists, including semaglutide.

Naltrexone-bupropionStrongVery common

Weight loss

Shown to cut about 2.5 to 5 kg more weight than placebo over a year in adults with overweight or obesity, depending on the analysis.

The numbers and sources

How common: Very common: more than 1 in 10 people.
Effect: At 56 weeks, weight changed by -1.3% on placebo, -5.0% on naltrexone 16 mg with bupropion and -6.1% on naltrexone 32 mg with bupropion. A loss of 5% or more occurred in 16%, 39% and 48% [1]. With intensive behavior therapy, weight fell 9.3% on the combination and 5.1% on placebo [2]. Across trials of at least a year, the combination produced 5.0 kg (95% CrI 3.96 to 5.94) more loss than placebo [3]. A meta-analysis built from the unpublished clinical study reports of 4 pivotal trials found 2.53 kg (95% CI 1.85 to 3.21) more loss than placebo, with GRADE certainty rated low [4].
Population: 1,742 adults with BMI 27 to 45 [1]; 793 adults, mean BMI 36.5 [2]; 28 RCTs with 29,018 adults [3]; 4 trials with 4,536 participants [4].
Sources: [1], [2], [3], [4]
Caveats: The pooled estimates disagree, 2.53 kg [4] against 5.0 kg [3], in part because [4] used the full clinical study reports. Half of COR-I participants completed 56 weeks, and the analysis carried the last observation forward [1]. COR-I was funded by Orexigen Therapeutics, the developer [1].

OrforglipronStrongVery common

Weight loss

Shown to cut weight about 11% on the top dose against 2% on placebo over 72 weeks in adults with obesity, alongside lifestyle intervention.

The numbers and sources

How common: Very common: more than 1 in 10 people.
Effect: In ATTAIN-1, body weight changed by -7.5% on 6 mg, -8.4% on 12 mg and -11.2% (95% CI -12.0 to -10.4) on 36 mg, against -2.1% on placebo, at 72 weeks. On 36 mg, 54.6% lost 10% or more and 18.4% lost 20% or more, against 12.9% and 2.8% on placebo [1]. In adults with type 2 diabetes (ATTAIN-2), weight changed by -9.6% on 36 mg against -2.5% on placebo, a difference of -7.1 points (95% CI -8.2 to -6.1) [2]. A network meta-analysis of obesity drugs estimated -9.9% (95% CI -12.4 to -7.5) for orforglipron against lifestyle change alone at one year, with moderate to high certainty [3]. A second meta-analysis found dose-related weight loss, larger in people without diabetes [4]. A third found a pooled difference of -5.25 kg (95% CI -6.72 to -3.77) against placebo, with high heterogeneity [5].
Population: 3,127 adults with obesity without diabetes [1]; 1,613 adults with a BMI of 27 or more and type 2 diabetes, 46.9% women, mean weight 101.4 kg [2]; 262 trials with 99,791 participants across 19 drugs [3]; 5 trials with 6,140 participants [4]; 5 trials with 2,672 participants [5].
Sources: [1], [2], [3], [4], [5]
Caveats: The meta-analyses draw on the same small set of trials, so they are not independent confirmations. Both phase 3 trials added lifestyle intervention and were funded by Eli Lilly, the maker [1][2]. The trial doses of 6, 12 and 36 mg correspond to label doses of 5.5, 9 and 17.2 mg [6].

OrlistatStrongVery common

Weight loss

Shown to cut about 2 to 3 kg more weight than placebo over a year, the smallest effect of five obesity drugs compared.

The numbers and sources

How common: Very common: more than 1 in 10 people.
Effect: Against placebo, orlistat reduced weight by 2.9 kg (95% CI 2.5 to 3.2) [1] and by 2.6 kg (95% CrI 2.16 to 3.04) at one year, the smallest effect of the five obesity drugs compared [2]. A loss of at least 5% occurred in 44% on orlistat against a median 23% on placebo [2]. A meta-analysis of 33 RCTs found a mean difference of 2.12 kg [3].
Population: 16 trials with 10,631 participants lasting 1 to 4 years [1]; 28 RCTs with 29,018 adults [2]; 33 RCTs with 9,732 participants [3].
Sources: [1], [2], [3]
Caveats: Attrition averaged 30 to 40% [1] and 30 to 45% [2]. The pooled trials mostly tested 120 mg three times daily with a reduced-calorie diet.

PhentermineStrongVery common

Weight loss with phentermine-topiramate

Shown to cut about 8 to 9 kg more weight than placebo over a year with phentermine-topiramate, rising with dose, alongside lifestyle programs.

The numbers and sources

How common: Very common: more than 1 in 10 people.
Effect: At 56 weeks, weight changed by -1.4 kg on placebo, -8.1 kg on 7.5/46 mg and -10.2 kg on 15/92 mg. A loss of at least 5% occurred in 21%, 62% and 70%, and a loss of at least 10% in 7%, 37% and 48% [1]. Across obesity drug trials of at least a year, phentermine-topiramate produced 8.8 kg (95% CrI 7.42 to 10.20) more loss than placebo, the largest of the five drugs compared [2]. A second network meta-analysis found 7.98 percentage points (95% CI 6.69 to 9.27) more loss than lifestyle change alone [3]. A meta-analysis of phentermine-topiramate trials found 7.73 kg (95% CI 6.60 to 8.85) more loss than placebo, rising with dose from 3.55 kg at 3.75/23 mg to 8.25 kg at 15/92 mg [4].
Population: 2,487 adults with BMI 27 to 45 and two or more weight-related conditions [1]; 28 RCTs with 29,018 adults [2]; 132 RCTs with 48,209 adults [3]; RCTs of phentermine-topiramate to April 2020 [4].
Sources: [1], [2], [3], [4]
Caveats: CONQUER was funded by Vivus, the maker [1]. Trials paired the drug with lifestyle programs. Attrition across obesity drug trials ran 30 to 45% [2]. Neither network meta-analysis included semaglutide 2.4 mg in its main ranking, and [3] reports semaglutide separately as larger.

RetatrutideGrey marketStrong

Weight loss in obesity without diabetes

Shown to lower body weight by up to 25% at 80 weeks in adults with obesity without diabetes, against about 4% on placebo.

The numbers and sources

Effect: At 80 weeks, body weight changed by -17.6% on 4 mg, -23.7% on 9 mg and -25.0% on 12 mg, against -3.9% on placebo. Differences from placebo were -19.8 and -21.0 percentage points for 9 mg and 12 mg [1]. In the phase 2 trial, weight changed by -8.7% on 1 mg, -17.1% on 4 mg, -22.8% on 8 mg and -24.2% on 12 mg at 48 weeks, against -2.1% on placebo [2]. Pooling 3 RCTs, weight fell 14.33% more than on placebo [3]. A network meta-analysis found mean weight loss of 11.0 kg on retatrutide, equal to the dual agonists and more than the GLP-1 receptor agonists (9.0 kg). The odds of losing 15% or more were 54.6 on retatrutide [4].
Population: 2,339 adults with obesity without diabetes in TRIUMPH-1 [1]; 338 adults with a BMI of 30 or more, or 27 or more with a weight-related condition, 51.8% men [2]; 3 RCTs with 878 adults with obesity, with or without diabetes [3]; 19 RCTs with 29,506 adults with a BMI of 25 or more, comparing six drugs and placebo [4].
Sources: [1], [2], [3], [4]
Caveats: Both trials were funded by Eli Lilly, the developer [1][2]. The sourced trials ran up to 80 weeks. The two meta-analyses searched before the phase 3 results were published, so they pooled phase 2 trials, including people with diabetes [3][4].

SGLT2 inhibitorsStrong

Body weight

Shown to lower body weight by about 1.3 to 1.9 kg in trials, in adults with type 2 diabetes and in adults with overweight and no diabetes.

The numbers and sources

Effect: In adults with type 2 diabetes, body weight fell by 1.88 kg (95% CI 1.66 to 2.11) across 43 trials [16], and by 1.80 kg (95% CI 0.11 to 3.50) more than on other diabetes drugs [14]. In adults with overweight or obesity and no diabetes, weight fell by 2.32 kg on an SGLT2 inhibitor against 1.01 kg on placebo over 12 weeks or more, a difference of 1.31 kg. Waist circumference and fat mass did not change against placebo [17].
Population: 22,528 patients with type 2 diabetes in 43 trials [16]; active-comparator studies in type 2 diabetes [14]; 750 adults without diabetes in 8 trials [17].
Sources: [16], [14], [17]
Caveats: Not an approved use. Heterogeneity was moderate in the largest analysis [16]. The trials in people without diabetes were small.

TirzepatideStrongVery common

Weight loss

Shown to lower body weight 15% to 21% at 72 weeks in adults with obesity without diabetes, against 3% on placebo, and more than semaglutide.

The numbers and sources

How common: Very common: more than 1 in 10 people.
Effect: At 72 weeks, body weight changed by -15.0% (95% CI -15.9 to -14.2) on 5 mg, -19.5% (95% CI -20.4 to -18.5) on 10 mg and -20.9% (95% CI -21.8 to -19.9) on 15 mg, against -3.1% on placebo. A loss of 20% or more occurred in 50% on 10 mg, 57% on 15 mg and 3% on placebo [1]. In an open-label head-to-head trial, weight changed by -20.2% (95% CI -21.4 to -19.1) on tirzepatide and -13.7% (95% CI -14.9 to -12.6) on semaglutide, and waist circumference by -18.4 cm and -13.0 cm [2]. Pooled across RCTs in adults without diabetes, weight changed by a mean difference of -16.32% against placebo (95% CI -18.35 to -14.29) [3]. Stratified by diabetes status, the difference was -17.15% without diabetes and -9.54% with it [4]. Across head-to-head studies, tirzepatide lost 4.28 percentage points more than semaglutide (95% CI -5.28 to -3.28) [5].
Population: 2,539 adults with a BMI of 30 or more, or 27 or more with a weight-related complication, without diabetes, mean weight 104.8 kg [1]; 751 adults with obesity without type 2 diabetes [2]; 6 RCTs in adults without diabetes [3]; 4,467 adults without and 2,174 with diabetes in 10 RCTs [4]; 41,381 participants in 10 studies [5].
Sources: [1], [2], [3], [4], [5]
Caveats: Both lead trials were funded by Eli Lilly, the maker [1][2]. The head-to-head trial was open-label [2], and the head-to-head meta-analysis included observational studies [5].

TopiramateStrong

Weight loss

Shown to lower weight by about 5.3 kg more than placebo in adults with overweight or obesity, and 3.4 kg in adults with type 2 diabetes, with more adverse events.

Compared with placebo [7][8][3]

The numbers and sources

Effect: Across 10 trials of at least 16 weeks, topiramate lowered weight 5.34 kg more than placebo (95% CI -6.12 to -4.56), and 6.58 kg in trials longer than 28 weeks at 96 to 200 mg a day. Withdrawal for adverse events was more likely (OR 1.94, 95% CI 1.64 to 2.29) [7]. In adults with obesity and type 2 diabetes, topiramate alone lowered weight 3.4 kg more than placebo (95% CI -3.79 to -3.04) and HbA1c by 0.4 points (95% CI -0.58 to -0.32), with more serious adverse events (RR 1.69, 95% CI 1.00 to 2.87) [8]. In the label's migraine trials, mean weight fell 2% at 50 mg, 3% at 100 mg and 4% at 200 mg, against 0% on placebo [3].
Population: 3,320 adults with overweight or obesity in 10 trials [7]; adults with obesity and type 2 diabetes in 5 trials [8]; adults in migraine trials [3].
Sources: [7], [8], [3]
Caveats: Topiramate alone is not approved for weight loss. All but one diabetes trial had high risk of bias [8].

BupropionModerate

Weight loss

Shown to produce about 2.8 kg more weight loss than placebo over 6 to 12 months in obesity trials. Not approved alone for this use.

The numbers and sources

Effect: In a meta-analysis of obesity drug trials, bupropion produced 2.77 kg more weight loss than placebo at 6 to 12 months (95% CI 1.1 to 4.5) when given alongside diet advice [14]. In depression trials, 14% on 300 mg a day and 19% on 400 mg a day lost more than 5 pounds, against 6% on placebo [15]. A meta-analysis of antidepressants and body weight found some weight loss with bupropion [16].
Population: Adults in randomized obesity trials [14]; 451 adults on sustained-release bupropion and 347 on placebo in depression trials [15]; antidepressant trials reporting weight [16].
Sources: [14], [15], [16]
Caveats: Heterogeneity was present in every analysis in [14], and long-term health outcomes were not measured. The combination of bupropion with naltrexone is covered on its own page.

DulaglutideModerate

Weight loss

Shown to lower weight modestly in type 2 diabetes, about 0.9 kg more than placebo overall and 1.9 kg at doses above 1 mg, in a meta-analysis of 18 trials.

Compared with placebo [8]; dulaglutide 1.5 mg [3]; semaglutide [4]

The numbers and sources

Effect: Dulaglutide lowered body weight against placebo (WMD -0.86 kg, 95% CI -1.22 to -0.49), BMI (WMD -0.68 kg/m2) and waist circumference (WMD -1.23 cm). At doses above 1 mg, weight fell 1.94 kg more (95% CI -2.54 to -1.34), and in trials over 18 weeks 1.42 kg more [8]. At 4.5 mg, weight fell 4.6 kg against 3.0 kg on 1.5 mg [3]. Semaglutide 1.0 mg lowered weight 3.55 kg more than dulaglutide 1.5 mg [4].
Population: 14,612 adults with type 2 diabetes in 18 trials with 33 arms [8]; 1,842 adults [3]; 1,201 adults [4].
Sources: [8], [3], [4]
Caveats: Dulaglutide is not approved for weight loss, and no trial in people without diabetes was located.

LiraglutideModerateVery common

Keeping weight off after a diet

Shown to keep off about 6.8 kg more than placebo for a year after a diet. Only liraglutide plus exercise also improved blood sugar and fitness.

The numbers and sources

How common: Very common: more than 1 in 10 people.
Effect: After a low-calorie diet run-in that cut 6.0% of weight, people on liraglutide lost a further 6.2% over 56 weeks and people on placebo 0.2%, a difference of -6.1% (95% CI -7.5 to -4.6). The run-in loss was held by 81.4% on liraglutide and 48.9% on placebo [5]. After an 8-week diet that cut a mean 13.1 kg, a year of liraglutide held 6.8 kg (95% CI 3.1 to 10.4) more off than placebo. Exercise alone held 4.1 kg more, and exercise plus liraglutide 9.5 kg more. Only the combination group improved HbA1c, insulin sensitivity and cardiorespiratory fitness. Body fat percentage fell 3.9 points with the combination, about twice as much as with either alone [6].
Population: 422 adults with overweight or obesity who lost at least 5% on the run-in [5]; 195 adults with BMI 32 to 43 without diabetes [6].
Sources: [5], [6]
Caveats: [5] was funded by Novo Nordisk. [6] was funded by the Novo Nordisk Foundation and others. The combination did not differ from liraglutide alone on weight (-2.7 kg, 95% CI -6.3 to 0.8) [6].

LiraglutideModerate

Body fat and visceral fat

Shown to cut fat mass and visceral fat more than placebo in people with overweight or obesity, with visceral fat down 12 to 23%. Lean mass results varied.

The numbers and sources

Effect: Across 15 placebo-controlled RCTs, liraglutide reduced total weight, fat mass and visceral fat more than placebo. Visceral fat fell 12.49% to 23% across studies. Lean mass results varied, with some studies reporting it held or rose and others reporting losses [7].
Population: 15 RCTs with 960 people with obesity or overweight [7].
Sources: [7]
Caveats: The review did not pool the results, and the authors could not calculate the share of weight lost as fat or lean mass [7].

RetatrutideGrey marketModerate

Weight loss in type 2 diabetes

Shown to lower body weight by about 12% to 19% at 80 weeks in adults with type 2 diabetes, against about 5% on placebo.

The numbers and sources

Effect: At 80 weeks, body weight changed by -11.9% on 4 mg, -16.8% on 9 mg and -18.8% on 12 mg, against -5.1% on placebo, differences of -6.9, -11.8 and -13.8 points [5]. In a 40-week trial without other glucose-lowering drugs, weight changed by -11.5%, -13.9% and -15.3%, against -2.6% on placebo [6].
Population: 1,152 adults with type 2 diabetes and a BMI of 27 or more, mean age 55.1, mean BMI 38.2 [5]; 537 adults with type 2 diabetes managed by diet and exercise, mean BMI 35.8 [6].
Sources: [5], [6]
Caveats: Weight loss in these trials was smaller than in TRIUMPH-1, which excluded people with diabetes [1]. Both trials were funded by Eli Lilly [5][6].

SemaglutideModerateVery common

Weight loss

Shown to lower body weight about 12.7 kg more than placebo over 68 weeks in adults with obesity without diabetes. Tirzepatide lowered weight more head to head.

The numbers and sources

How common: Very common: more than 1 in 10 people.
Effect: At 68 weeks, body weight changed by -14.9% on semaglutide and -2.4% on placebo, a difference of -12.4 percentage points (95% CI -13.4 to -11.5), or -12.7 kg. A loss of 15% or more occurred in 50.5% on semaglutide and 4.9% on placebo [1]. In an open-label head-to-head trial, weight changed by -13.7% (95% CI -14.9 to -12.6) on semaglutide and -20.2% (95% CI -21.4 to -19.1) on tirzepatide at 72 weeks [2].
Population: 1,961 adults with a BMI of 30 or more, or 27 or more with a weight-related condition, without diabetes [1]; 751 adults with obesity without type 2 diabetes [2].
Sources: [1], [2]
Caveats: Both trials added lifestyle intervention or diet and activity. STEP 1 was funded by Novo Nordisk [1]; the head-to-head trial by Eli Lilly, maker of tirzepatide [2].

TirzepatideModerateVery common

Keeping weight off while staying on treatment

Shown to keep weight off in adults who stayed on treatment, while those switched to placebo regained 14%. Only people who finished a lead-in took part.

The numbers and sources

How common: Very common: more than 1 in 10 people.
Effect: After 36 weeks on tirzepatide (mean loss 20.9%), people randomized to continue lost a further 5.5% by week 88, while those switched to placebo regained 14.0%, a difference of -19.4% (95% CI -21.2 to -17.7). On tirzepatide, 89.5% kept at least 80% of their earlier loss, against 16.6% on placebo [6]. In SURMOUNT-MAINTAIN, after 60 weeks of open-label treatment, weight change from baseline at week 112 was -21.9% for those continuing the maximum tolerated dose, -16.6% on a reduced 5 mg dose and -9.9% on placebo (difference against placebo -12.0%, 95% CI -13.8 to -10.1). Rescue tirzepatide, offered to those who regained more than half their loss, was given to 8%, 25% and 67% of the three groups [7].
Population: 670 adults with obesity or overweight without diabetes, 71% women, mean weight 107.3 kg, in a 52-week randomized withdrawal [6]; 378 adults with obesity randomized at week 60, 65% women, mean weight 113.8 kg [7].
Sources: [6], [7]
Caveats: Two trials, both funded by Eli Lilly. Each randomized only people who completed an open-label lead-in [6][7].

TopiramateModerate

Binge eating disorder

Shown to reduce binge episodes by about 1.3 a week and weight by about 4.9 kg against placebo in binge eating disorder, with more withdrawals for safety reasons.

Compared with placebo, with or without psychotherapy [9]

The numbers and sources

Effect: Topiramate lowered binge episodes per week (MD -1.31, 95% CI -2.58 to -0.03), binge days per week (MD -0.98, 95% CI -1.80 to -0.16) and weight (MD -4.91 kg, 95% CI -6.42 to -3.41). Withdrawals for safety reasons were more frequent (RR 1.90, 95% CI 1.13 to 3.18) [9].
Population: 528 people with binge eating disorder in 3 trials [9].
Sources: [9]
Caveats: Only three trials, with very high heterogeneity for binge outcomes (I² 94%) [9].

ADHD stimulantsLimited

Weight loss

One trial found adults with binge eating disorder lost 4.9 kg on lisdexamfetamine 50 or 70 mg over 11 weeks, against 0.1 kg on placebo.

The numbers and sources

Effect: In the 11-week binge eating trial, mean weight change was -0.1 kg on placebo, -3.1 kg on 30 mg, -4.9 kg on 50 mg and -4.9 kg on 70 mg [8]. In a 4-week ADHD trial, weight loss was reported as an adverse reaction by 10% of adults on extended-release mixed amphetamine salts and none on placebo [17]. The lisdexamfetamine label states that it is not indicated for weight loss, that other sympathomimetic drugs used for weight loss have been associated with serious cardiovascular adverse events, and that its safety and effectiveness for obesity have not been established [18].
Population: Adults with moderate to severe binge eating disorder in an 11-week trial [8]; 191 adults with ADHD on the drug and 64 on placebo [17].
Sources: [8], [17], [18]
Caveats: Weight was a secondary measure in a short trial of people with binge eating disorder, analyzed post hoc. No trial of these drugs for obesity was located. Not an approved use.

DulaglutideLimited

Higher doses of 3 mg and 4.5 mg

One trial found 4.5 mg lowered HbA1c 0.24 points more and weight 1.6 kg more than 1.5 mg over 36 weeks, with more nausea and vomiting.

Compared with dulaglutide 1.5 mg [3]

The numbers and sources

Effect: At 36 weeks, HbA1c fell 1.77 points on 4.5 mg and 1.54 on 1.5 mg (difference -0.24, P under 0.001). The 3 mg dose beat 1.5 mg only in the on-treatment analysis (-0.17 points). Weight fell 4.6 kg on 4.5 mg and 3.0 kg on 1.5 mg. Nausea occurred in 13.4%, 15.6% and 16.4%, and vomiting in 5.6%, 8.3% and 9.3%, on 1.5, 3 and 4.5 mg [3].
Population: 1,842 adults with type 2 diabetes on metformin, mean HbA1c 8.6% and BMI 34.2, over 52 weeks [3].
Sources: [3]
Caveats: One trial with no placebo arm, funded by the manufacturer.
Why limited: This rests on one trial, of 1,842 people. Strength counts independent studies that agree, so one trial is limited at any size.

Naltrexone-bupropionLimited

Weight and blood sugar in type 2 diabetes

One trial found more weight loss, 5.0% against 1.8%, and a larger HbA1c drop than placebo in adults with type 2 diabetes.

The numbers and sources

Effect: Weight changed by -5.0% on the combination and -1.8% on placebo at 56 weeks. HbA1c fell 0.6 points against 0.1 points, and 44.1% against 26.3% reached an HbA1c under 7% [5].
Population: 505 adults with type 2 diabetes and overweight or obesity, mean HbA1c 8.0% [5].
Sources: [5]
Caveats: One trial.

OrforglipronLimited

Keeping weight off after switching from injectable drugs

One trial found people switched from tirzepatide or semaglutide kept about 75 to 79% of their weight loss at a year, against 38 to 49% on placebo.

The numbers and sources

Effect: People who had lost weight on tirzepatide or semaglutide and were switched to orforglipron kept a model-based estimate of 74.7% (after tirzepatide) and 79.3% (after semaglutide) of their weight reduction at week 52, against 49.2% and 37.6% on placebo. The differences were 25.5 points (95% CI 14.5 to 36.5) and 41.7 points (95% CI 24.4 to 59.0) [11].
Population: 376 adults previously treated in SURMOUNT-5, 205 after tirzepatide and 171 after semaglutide [11].
Sources: [11]
Caveats: One trial, one year long, with no arm that stayed on the injectable drug, so it does not compare switching with continuing [11].

PhentermineLimited

Weight held at two years on phentermine-topiramate

One extension trial found weight held about 9 to 10.5% below baseline at 2 years on phentermine-topiramate, against 1.8% on placebo.

The numbers and sources

Effect: At week 108, weight changed from baseline by -1.8% on placebo, -9.3% on 7.5/46 mg and -10.5% on 15/92 mg. Incident diabetes was lower on treatment than placebo. Adverse event rates were lower in weeks 56 to 108 than in weeks 0 to 56 [5].
Population: 676 of 866 eligible CONQUER participants who chose to continue, 84% completing [5].
Sources: [5]
Caveats: One extension trial at selected sites, with participants who chose to continue. Last observation carried forward.

PhentermineLimited

Weight loss with phentermine alone

One 12-week trial found 8.1 kg lost on phentermine against 1.7 kg on placebo. No year-long review of phentermine alone was sourced.

The numbers and sources

Effect: Over 12 weeks, people on phentermine 30 mg lost 8.1 kg and people on placebo 1.7 kg. A loss of 5% or more occurred in 95.8% and 20.8%. Blood pressure did not differ between groups [6]. In health records, people who used phentermine continuously for more than 12 months had lost 7.4% more weight at 24 months than people who used it for 3 months or less [7].
Population: 74 Korean adults with obesity and controlled diabetes, hypertension or dyslipidemia [6]; 13,972 adults with a first phentermine fill, 84% women [7].
Sources: [6], [7]
Caveats: [6] is a small 12-week trial. [7] is observational, and duration of use was not randomized. No meta-analysis of phentermine alone over a year or more was sourced.

RetatrutideGrey marketLimited

Body fat

One trial found fat mass fell up to 26% over 36 weeks in adults with type 2 diabetes, against about 5% on placebo.

The numbers and sources

Effect: At 36 weeks, total fat mass on DXA fell 4.9% on 0.5 mg, 15.2% on 4 mg, 26.1% on 8 mg and 23.2% on 12 mg, against 4.5% on placebo and 2.6% on dulaglutide. Differences from placebo were -0.4 (95% CI -4.0 to 3.2), -10.7 (95% CI -17.2 to -4.2), -21.6 (95% CI -27.1 to -16.1) and -18.7 (95% CI -25.1 to -12.3) points. The authors report the share of weight lost as lean mass was similar to other obesity treatments [9].
Population: 189 adults with type 2 diabetes in a substudy of a phase 2 trial, 103 of them with scans at baseline and week 36 [9].
Sources: [9]
Caveats: A substudy of one phase 2 trial. The analysis used participants with scans before stopping the drug. Funded by Eli Lilly [9].

SemaglutideLimited

Weight loss at the 7.2 mg dose

One trial found the 7.2 mg dose lowered weight about 19% at 72 weeks, 3 points more than 2.4 mg, in adults with obesity without diabetes.

The numbers and sources

Effect: At 72 weeks, body weight changed by -18.7% on semaglutide 7.2 mg, -15.6% on 2.4 mg and -3.9% on placebo. The difference was -3.1 percentage points against 2.4 mg (95% CI -4.7 to -1.6) and -14.8 points against placebo (95% CI -16.2 to -13.4). Against 2.4 mg, the odds of losing 20% or more were 1.8 times higher (95% CI 1.3 to 2.4) and of losing 25% or more 2.4 times higher (95% CI 1.6 to 3.5). The difference in waist circumference against placebo was -11.7 cm (95% CI -13.0 to -10.4) [3].
Population: 1,407 adults with a BMI of 30 or more without diabetes, 73.7% women, mean weight 113.0 kg, randomized 5 to 1 to 1 to 7.2 mg (1,005), 2.4 mg (201) or placebo (201), with a lifestyle intervention, for 72 weeks [3].
Sources: [3]
Caveats: One trial, with 201 people in the 2.4 mg comparison arm. Funded by Novo Nordisk [3]. Gastrointestinal events and dysesthesia were more common at 7.2 mg than at 2.4 mg (see Risks).
Why limited: This rests on one trial, of 1,407 people. Strength counts independent studies that agree, so one trial is limited at any size.

SemaglutideLimited

Keeping weight off while staying on treatment

One trial found people who stayed on semaglutide lost a further 7.9%, while those switched to placebo regained 6.9%. Only people who tolerated the full dose took part.

The numbers and sources

Effect: After 20 weeks on semaglutide (mean loss 10.6%), people randomized to continue lost a further 7.9% by week 68, while those switched to placebo regained 6.9%, a difference of -14.8 points (95% CI -16.0 to -13.5). Waist circumference fell 9.7 cm more and systolic blood pressure 3.9 mm Hg more with continued treatment [4].
Population: 803 adults with overweight or obesity without diabetes, 79% women, mean weight 107.2 kg, in a 48-week randomized withdrawal [4].
Sources: [4]
Caveats: One trial. Only people who reached the full dose in the run-in were randomized, so the results describe people who tolerated it.

TirzepatideLimited

Appetite and food intake

One small trial found about 525 fewer calories eaten at a test lunch, and less hunger and craving, at week 3 in adults without diabetes.

The numbers and sources

Effect: At week 3, tirzepatide cut energy intake at a self-serve lunch by 524.6 kcal more than placebo (95% CI -648.1 to -401.0). Self-reported appetite, food cravings, tendency to overeat and hunger fell against placebo [8].
Population: 114 adults without diabetes, BMI 27 to 50, in a 6-week phase 1 trial [8].
Sources: [8]
Caveats: One small trial that measured a single test meal.

DulaglutideLimited

Compared with semaglutide

One head-to-head trial found semaglutide lowered HbA1c about 0.4 points more and weight 2.3 to 3.6 kg more than dulaglutide at matched dose levels over 40 weeks.

Compared with semaglutide [4]

The numbers and sources

Effect: HbA1c fell 1.4 points on dulaglutide 1.5 mg and 1.8 on semaglutide 1.0 mg (difference -0.41), and 1.1 on dulaglutide 0.75 mg against 1.5 on semaglutide 0.5 mg (difference -0.40). Weight fell 3.0 kg against 6.5 kg (difference -3.55 kg) and 2.3 kg against 4.6 kg. Gastrointestinal disorders occurred in 48% on dulaglutide 1.5 mg and 44% on semaglutide 1.0 mg [4].
Population: 1,201 adults with type 2 diabetes on metformin in 16 countries [4].
Sources: [4]
Caveats: Open label, funded by the maker of semaglutide. Dulaglutide still lowered HbA1c and weight from baseline in both arms [4].
Why limited: This rests on one trial, of 1,201 people. Strength counts independent studies that agree, so one trial is limited at any size.

LevothyroxineLimited

Weight loss in obesity

Limited evidence: small studies could not establish a consistent effect of T3 or T4 on weight loss in obesity, and the therapy induced subclinical hyperthyroidism.

The numbers and sources

Effect: During calorie restriction in people with obesity, T3 lowered TSH and T4, but consistent effects of T3 or T4 on weight loss, protein breakdown, metabolic rate or heart rate could not be established. The review found the therapy induced subclinical hyperthyroidism [9].
Population: RCTs and prospective controlled studies of T3 or T4 in obesity [9].
Sources: [9]
Caveats: Few small studies of poor quality, with variable endpoints [9].

RapamycinLimited

Healthspan measures in healthy older adults

Small trials found no change in visceral fat, cognition or physical performance in healthy older adults, with only scattered gains in subgroups.

The numbers and sources

Effect: Over 48 weeks, weekly rapamycin 5 mg or 10 mg did not change visceral fat on DXA, the primary outcome, against placebo (p = 0.942). Blood biomarkers stayed in normal ranges. Lean tissue mass and self-reported pain improved in women on 10 mg, and emotional well-being and general health scores improved on 5 mg. No other effects were significant [1]. In a pilot in adults aged 70 to 95, 8 weeks or more of rapamycin 1 mg daily did not change cognitive, physical performance or self-rated health measures, or glucose tolerance [2].
Population: Healthy adults in a decentralized 48-week trial [1]; 25 adults with mean age 80.5 [2].
Sources: [1], [2]
Caveats: The positive findings in [1] were in subgroups among many secondary outcomes. [1] used compounded rapamycin. Both trials were small.

Hormone therapy

Testosterone therapyStrongStudied in men

Fat-free mass and body fat in middle-aged and older men

Shown to add about 1.6 kg of fat-free mass and cut about 1.6 kg of body fat in middle-aged and older men, with no change in weight.

The numbers and sources

Effect: Testosterone raised fat-free mass by 1.6 kg (95% CI 0.6 to 2.6), a 2.7% rise over baseline, and cut total body fat by 1.6 kg (95% CI 0.6 to 2.5), a 6.2% drop. Body weight did not change [2]. A 2026 systematic review of 8 double-blind placebo-controlled trials in men with obesity and type 2 diabetes or metabolic syndrome found the most consistent effect was more lean mass and less fat mass [3].
Population: 1,083 men in 29 RCTs, weighted mean age 64.5, mean baseline testosterone 10.9 nmol/L [2]; men with functional secondary hypogonadism, obesity and type 2 diabetes or metabolic syndrome in 8 RCTs [3].
Sources: [2], [3]
Caveats: The meta-analysis is from 2005, and dose and preparation explained some of the heterogeneity between trials [2]. The 2026 review was not pooled and rated certainty for lean and fat mass as low [3]. Fat-free mass counts water and organs as well as muscle.

DHEAModerate

Lean mass and fat mass

Shown to raise lean mass by about 0.45 kg in adults, though a 2-year trial in older adults found no change in body composition.

The numbers and sources

Effect: Pooled RCTs found DHEA raised lean body mass by 0.45 kg (95% CI 0.15 to 0.75) and lowered fat mass by 0.85% (95% CI 0.51 to 1.18). Body weight did not change [1]. In elderly men, fat mass fell by an SMD of -0.35 (95% CI -0.65 to -0.05), but the effect disappeared after adjusting for rises in testosterone and estradiol [2]. A 2-year RCT found no significant effect on body composition in men or women [3].
Population: Adults in randomized trials [1]; 1,353 elderly men in 25 placebo-controlled RCTs, mean follow-up 36 weeks [2]; 87 elderly men and 57 elderly women with low DHEA-S over 2 years [3].
Sources: [1], [2], [3]
Caveats: The pooled lean mass gain is small, and the one long trial did not find it.

Growth hormoneModerate

Body composition in healthy older adults

Shown to lower fat mass about 2.1 kg and raise lean body mass about 2.1 kg in healthy older adults, with no change in weight.

The numbers and sources

Effect: Against no growth hormone, fat mass fell 2.1 kg (95% CI 1.35 to 2.8) and lean body mass rose 2.1 kg (95% CI 1.3 to 2.9). Weight did not change (0.1 kg, 95% CI -0.7 to 0.8). Total cholesterol fell 0.29 mmol/L, not significantly after adjusting for body composition. Bone density and other lipids did not change [1].
Population: 18 study populations with 220 treated participants, mean age 69, mean BMI 28, mean treatment 27 weeks [1].
Sources: [1]
Caveats: Most trials were small, and some outcomes were measured too rarely to pool [1]. The review was funded by AHRQ and the NIA. Lean body mass includes water, not only muscle.

Growth hormoneModerate

Visceral fat and thigh muscle in adults with obesity

Shown to lower visceral fat modestly and raise thigh muscle area with low-dose growth hormone in adults with obesity and no deficiency.

The numbers and sources

Effect: In adults with obesity and no growth hormone deficiency, low-dose growth hormone lowered visceral fat by an SMD of -0.34 (95% CI -0.57 to -0.12) and raised thigh muscle area by 6.33 cm² (95% CI 1.72 to 10.95) against placebo [4].
Population: 420 adults aged 18 to 65 in 10 RCTs lasting 4 to 72 weeks [4].
Sources: [4]
Caveats: Small trials with wide differences in length. Fasting glucose rose (see Risks) [4].

Growth hormoneModerate

Body composition and quality of life in growth hormone deficiency

Shown to lower body fat about 2.6 kg and raise lean mass about 1.4 kg in adults with growth hormone deficiency. Quality of life improved in most trials.

The numbers and sources

Effect: In adults with confirmed deficiency, growth hormone lowered weight by 2.31 kg (95% CI 1.96 to 2.66) and body fat by 2.56 kg (95% CI 2.16 to 2.97), and raised lean body mass by 1.38 kg (95% CI 1.10 to 1.65). BMI and bone density did not change. Quality of life improved in 11 of 16 trials, though the data could not be pooled [6].
Population: 54 RCTs with more than 3,400 adults with growth hormone deficiency [6].
Sources: [6]
Caveats: Trial quality was rated fair [6]. These results describe people with a diagnosed deficiency, not healthy adults.

hCGModerate

Weight loss with the hCG diet

Not shown to cause weight loss, fat redistribution or less hunger with the hCG diet in people with obesity.

The numbers and sources

Effect: Of the 12 studies scoring 50 or more points for method quality, all controlled, one reported hCG as a useful adjunct. The authors found no evidence that hCG brought about weight loss or fat redistribution, reduced hunger or improved well-being [1].
Population: 8 controlled and 16 uncontrolled trials of hCG with the Simeons regimen in people with obesity [1].
Sources: [1]
Caveats: Method scores ranged from 16 to 73 of 100, and the meta-analysis is from 1995.

Peptides and SARMs

TesamorelinStrong

Visceral (deep abdominal) fat in people with HIV

Shown to cut deep abdominal fat about 15% more than placebo in adults with HIV on treatment. Fat under the skin did not change.

The numbers and sources

Effect: At 26 weeks, visceral fat on CT changed by -15.2% on tesamorelin and +5.0% on placebo [1]. In the second phase 3 trial it changed by -10.9% against -0.6% [2]. Pooled across both trials, visceral fat changed by -24 cm² against +2 cm², a treatment effect of -15.4%. Fat under the skin of the abdomen did not differ from placebo (treatment effect -0.6%) [3]. In people who stayed on treatment to 52 weeks, visceral fat was 17.5% below baseline [3]. Two meta-analyses found visceral fat fell against placebo by a mean difference of -21.47 (95% CI -34.73 to -8.22, I² 74%) [4] and -27.71 cm² (95% CI -38.37 to -17.06) [5]. Trunk fat fell by about 1.2 kg and waist circumference by 1.61 cm (95% CI -2.28 to -0.95) [4][5].
Population: 412 adults with HIV on antiretroviral therapy with abdominal fat accumulation, 86% men [1]; 404 adults in the second trial [2]; 806 in the pooled analysis [3]; 909 people with HIV-associated lipodystrophy in 4 RCTs [4]; 5 RCTs against placebo [5].
Sources: [1], [2], [3], [4], [5]
Caveats: Every trial enrolled people with HIV on antiretroviral therapy, so the results do not describe people without HIV. Visceral fat is a scan measure, and no trial measured heart attacks or deaths. The two meta-analyses draw on largely the same trials. One found no significant change in fat under the skin or in BMI [5].

MOTS-cGrey marketUntested

Weight, fat loss and metabolism

Not studied in people. In mice, MOTS-c treatment prevented the obesity a high-fat diet otherwise caused.

No study in people. This rests on animal studies, lab studies.

The numbers and sources

Effect: MOTS-c treatment in mice prevented diet-induced obesity. Its primary target organ appeared to be skeletal muscle, where it inhibited the folate cycle and the purine synthesis tied to it, leading to activation of AMPK, an energy-sensing enzyme [9].
Population: Mice, and cells in the lab [9].
Sources: [9], [10]
Caveats: Studies in people have measured the MOTS-c the body makes, not MOTS-c given as a treatment. In one, circulating levels were higher in 32 adults with obesity than in 22 lean adults, and did not change 6 months after bariatric surgery in 10 patients despite lower BMI [10]. FDA found no human exposure data for MOTS-c by any route [3].

CJC-1295 and ipamorelinGrey marketNo research yet

Fat loss

We haven't sourced research on this yet.

Supplements

Alpha-lipoic acidStrong

Weight loss

Shown to add about 0.6 to 1.3 kg of weight loss over placebo across trials. The analyses disagree on waist size.

The numbers and sources

Effect: Weight loss was 1.27 kg greater on alpha-lipoic acid than placebo (95% CI 0.25 to 2.29) and BMI 0.43 lower [6]. A second analysis found weight -0.69 kg (95% CI -1.27 to -0.10) and BMI -0.38. Waist circumference did not change [7]. A 2026 analysis of 63 trials found weight -0.64 kg (95% CI -1.04 to -0.24), fat mass -1.42 kg (95% CI -2.53 to -0.31) and waist circumference -1.10 cm (95% CI -1.66 to -0.54) against control [8].
Population: 10 trials [6]; 12 trials [7]; 63 randomized trials [8].
Sources: [6], [7], [8]
Caveats: Dose did not predict effect [6]. Trials were short. The two analyses that measured waist size disagree [7][8].

ChromiumStrong

Weight loss

Shown to lower body weight by about 1.1 kg over placebo after 12 to 16 weeks in overweight or obese adults, on low-quality evidence.

The numbers and sources

Effect: After 12 to 16 weeks, body weight was 1.1 kg lower on chromium picolinate than placebo (95% CI -1.7 to -0.4). No dose gradient was found across 200 to 1,000 µg a day [8]. An earlier analysis also found -1.1 kg (95% CI -1.8 to -0.4), and the effect lost significance without one trial (-0.9 kg, 95% CI -2.0 to 0.2) [9].
Population: 392 overweight or obese adults in 6 trials pooled, 9 trials with 622 people reviewed [8]; 489 people in 10 trials [9].
Sources: [8], [9]
Caveats: The Cochrane authors rated the evidence low quality and called the effect of debatable clinical relevance [8]. The earlier analysis asked manufacturers for unpublished studies [9].

CLAStrong

Body weight

Shown to lower body weight by about 0.35 to 0.7 kg more than placebo in adults, a change that may not be clinically important.

The numbers and sources

Effect: In trials of 6 months or more, weight loss was 0.70 kg greater than placebo (95% CI -1.09 to -0.32) [2]. Across 70 RCTs, body weight was 0.35 kg lower (95% CI -0.54 to -0.15) and BMI 0.15 kg/m² lower [3].
Population: Overweight and obese adults [2]; adults [3].
Sources: [2], [3]
Caveats: The authors of [3] wrote that the weight change may not reach clinical importance.

L-carnitineStrong

Weight and fat loss

Shown to lower body weight about 1.2 kg in adults, mostly with overweight or obesity. Body fat percentage did not change, and the effect shrank over time.

The numbers and sources

Effect: Across 37 RCTs (2,292 participants), L-carnitine lowered body weight by 1.21 kg (95% CI -1.73 to -0.68), BMI by 0.24 kg/m² and fat mass by 2.08 kg (95% CI -3.44 to -0.72), with no change in waist circumference or body fat percentage. Only the weight effect held in high-quality trials [1]. In 9 RCTs (911 adults), weight fell 1.33 kg more than control (95% CI -2.09 to -0.57), and the effect shrank the longer people took it (p = 0.002) [2]. An umbrella meta-analysis pooling 8 meta-analyses (16,352 participants) found lower weight (ES -1.11, 95% CI -1.90 to -0.33), BMI (ES -0.33) and waist circumference (ES -1.34, 95% CI -1.83 to -0.85) [3].
Population: Adults, mostly with overweight or obesity [1][2]. Trials of 8 to 30 weeks at 150 to 4,000 mg a day [3].
Sources: [1], [2], [3]
Caveats: Body fat percentage did not change [1]. The reviews differ on waist circumference [1][3]. Heterogeneity was high for weight and BMI in the umbrella analysis (I² 90.6% and 89.8%) [3].

BerberineModerate

Body weight

Shown to lower body weight by about 0.9 kg in adults. A 6-month trial found no change in visceral or liver fat.

The numbers and sources

Effect: Across 23 RCTs, berberine lowered body weight by 0.88 kg (95% CI -1.36 to -0.39), BMI by 0.48 kg/m² and waist circumference by 1.32, with no change in waist-to-hip ratio [9]. In a 6-month double-blind trial, 1 g a day did not change visceral fat area (difference 1.4%, 97.5% CI -2.4% to 5.2%) or liver fat content (0.9%, 97.5% CI -0.4% to 2.1%) against placebo [10].
Population: Adults [9]. 337 adults without diabetes with obesity and fatty liver disease at 11 hospitals in China [10].
Sources: [9], [10]
Caveats: The authors call for better reporting of purity, potency and dose, and note lack of blinding and randomization in some trials [9]. The 6-month trial measured fat by CT and its abstract does not report body weight [10].

Black seed oilModerate

Body weight

Shown to lower weight by about 1.6 to 1.8 kg in adults, with very high variation. In type 2 diabetes, weight did not change significantly.

The numbers and sources

Effect: In 10 RCTs, weight fell 1.76 kg (95% CI -3.34 to -0.17, I² 87.4%) against placebo. BMI fell 0.85 kg/m² in 11 trials. Waist size did not change significantly in 5 trials (-4.04 cm, I² 97.8%) [5]. In 31 trials (2,145 people) with metabolic diseases, weight fell 1.59 kg (95% CI -3.03 to -0.15) and BMI 0.51 kg/m², with no change in waist or hip size [6]. In 16 RCTs in type 2 diabetes, body weight and BMI did not change significantly [7].
Population: 875 adults, 64% male, in 13 RCTs [5]. Adults with type 2 diabetes, obesity or other metabolic diseases [6][7].
Sources: [5], [6], [7]
Caveats: Heterogeneity was very high [5]. The reviews disagree in type 2 diabetes [7]. The 2026 authors note variable study quality [6].

CLAModerate

CLA combined with exercise

Shown to lower body fat and insulin resistance more than exercise alone, mainly in women, people with a BMI of 25 or more and after 4 weeks.

The numbers and sources

Effect: In 20 trials of CLA plus exercise against exercise alone, body fat fell more (SMD -0.42, 95% CI -0.70 to -0.14, I² 65%) and insulin resistance fell more (SMD -0.25, 95% CI -0.44 to -0.06). Body weight, exercise performance and blood lipids did not differ [5].
Population: 18 RCTs and 2 crossover trials [5].
Sources: [5]
Caveats: Effects were seen mainly in subgroups with BMI of 25 or more, women and interventions longer than 4 weeks [5].

Green tea extractModerate

Fat burning during exercise

Shown to raise fat burning slightly during and after exercise. These trials did not measure body fat.

The numbers and sources

Effect: In a 2026 GRADE-assessed meta-analysis of 9 trials, green tea extract raised fat oxidation during exercise by 0.2 g per minute (95% CI 0.04 to 0.36) and after exercise by 0.04 g per minute (95% CI 0.01 to 0.08). Carbohydrate oxidation fell after exercise (-0.16 g per minute) and did not change during it [5].
Population: Participants in 9 randomized trials measuring substrate use around exercise [5].
Sources: [5]
Caveats: One meta-analysis, with certainty rated low to high depending on the outcome [5]. Fat oxidation rate is not fat loss, and these trials did not measure body fat.

InositolModerate

Weight, blood sugar and lipids

Shown to lower BMI slightly, about 0.6 kg/m², and glucose, triglycerides and blood pressure in adults across several conditions, at low certainty for some.

The numbers and sources

Effect: In 18 RCTs (898 participants) of at least 4 weeks, inositol lowered BMI by 0.57 kg/m² (95% CI -1.10 to -0.03), waist circumference by 2.36 cm, glucose by 7.25 mg/dL, HOMA-IR by 1.21, triglycerides by 29.80 mg/dL, LDL cholesterol by 5.15 mg/dL, and systolic and diastolic pressure by 5.34 and 6.12 mm Hg [11].
Population: Adults in RCTs across several conditions [11].
Sources: [11]
Caveats: Certainty was low to very low for BMI, waist and blood pressure, and moderate for glucose, insulin and HOMA-IR. Heterogeneity was high for most outcomes, and the authors note a high risk of bias in the trials [11].

TurmericModerate

Body weight

Shown to lower body weight about 2 kg in adults with type 2 diabetes or prediabetes. Reviews disagree on BMI.

The numbers and sources

Effect: In 20 RCTs, turmeric or curcumin lowered body weight by 1.9 kg (95% CI -2.9 to -0.9) and waist by 1.9 cm in type 2 diabetes, without changing BMI, and lowered weight by 2.5 kg in prediabetes [33]. In 9 RCTs (699 adults with type 2 diabetes), weight fell 1.65 kg, BMI 0.69 kg/m² and waist 0.93 cm [34]. The 63-trial pooled analysis found no significant BMI change [7].
Population: Adults with prediabetes or type 2 diabetes [33][34][7].
Sources: [33], [34], [7]
Caveats: GRADE certainty was low for weight in type 2 diabetes [33]. The reviews disagree on BMI [33][34][7]. One review was not registered [34].

5-HTPLimited

Appetite and weight

One small trial found obese adults on 900 mg a day lost weight, ate less carbohydrate and felt full sooner than on placebo.

The numbers and sources

Effect: In 20 obese patients given 900 mg a day or placebo for two 6-week periods, those on 5-HTP lost weight in both periods, ate less carbohydrate and reported early satiety [6].
Population: 20 obese adults [6].
Sources: [6]
Caveats: One small trial from 1992 [6].

CaffeineLimited

Fat loss

Limited evidence: across 13 trials, higher caffeine intake went with more weight and fat loss, with very high variation between trials.

The numbers and sources

Effect: Across 13 RCTs (606 participants), the pooled dose-response coefficient favored reductions in weight (beta 0.29, 95% CI 0.19 to 0.40), BMI (beta 0.23) and fat mass (beta 0.36). The authors estimate each doubling of intake was associated with 22% more weight reduction, 17% more BMI reduction and 28% more fat mass reduction [11].
Population: Adults in 13 RCTs [11].
Sources: [11]
Caveats: Heterogeneity was 91% to 94% across outcomes. The method models effect per doubling of intake on a log scale rather than reporting kilograms lost against placebo.

Protein powderLimited

Weight and fat loss

Limited evidence: one review found whey favored small reductions in body weight and fat mass in adults with overweight or obesity.

The numbers and sources

Effect: In 9 RCTs in people with overweight or obesity, whey favored reductions in body weight (mean difference 0.56, 95% CI 0.30 to 0.81) and fat mass (1.12, 95% CI 0.77 to 1.47), with lower blood pressure, glucose and total cholesterol [12].
Population: Adults with overweight or obesity [12].
Sources: [12]
Caveats: The abstract does not state units and lists lean mass (0.77) among the reductions favoring whey, which is hard to read. One meta-analysis of 9 trials.

White kidney bean extractLimited

Appetite

Small trials found less desire to eat after one meal with a bean extract, and more fullness over 2 months with a bean and artichoke blend, against placebo.

Compared with placebo [9][10]

The numbers and sources

Effect: In 12 healthy volunteers, 100 mg of a bean extract with a mixed meal lowered the desire to eat over 3 hours against placebo (P = 0.02), and blood ghrelin did not rebound in the third hour as it did on placebo (P = 0.04) [9]. In 39 overweight adults, an extract of Phaseolus vulgaris with artichoke (Cynara scolymus) for 2 months raised satiation scores and lowered the susceptibility-to-hunger score, which did not change on placebo [10]. In rats, a bean extract lowered food intake and body weight gain in a dose-dependent way, an effect blocked by a CCK receptor antagonist [11].
Population: 12 healthy volunteers, one meal [9]. 39 overweight adults, 20 on the blend and 19 on placebo [10]. Rats [11].
Sources: [9], [10], [11]
Caveats: Two small trials. The first tested a single meal [9], and the second a combination with artichoke, so the bean extract's share is unknown [10]. Appetite was self-rated.

Beta-glucanModerate

Body weight

Mixed results: one review found weight about 0.8 kg lower, and a later, larger review in adults with overweight found no change.

The numbers and sources

Effect: In 20 trials, cereal beta-glucan lowered body weight by 0.77 kg (95% CI 0.04 to 1.49) and BMI by 0.62. Waist circumference and energy intake did not change [7].
Population: Adults in randomized trials [7].
Sources: [7]
Caveats: A small average change. A later meta-analysis of 49 studies (3,854 people) with a BMI of 25 or more found no change in body weight [8].

CLAModerate

Fat mass

Mixed results: pooled trials found about 0.4 to 1.3 kg more fat loss than placebo in adults, while the high-quality subgroup showed no change.

The numbers and sources

Effect: Across 18 placebo-controlled trials, CLA at a median 3.2 g a day reduced fat mass by 0.09 kg a week more than placebo, with the effect linear up to 6 months [1]. In 7 trials lasting at least 6 months, fat loss was 1.33 kg greater than placebo (95% CI -1.79 to -0.86, I² 54%) [2]. In 70 RCTs with 4,159 participants, fat mass was 0.44 kg lower (95% CI -0.66 to -0.23) and body fat 0.77 percentage points lower, but the high-quality subgroup showed no change in fat mass or body fat percentage [3].
Population: Adults in RCTs [1][3]; overweight and obese adults [2].
Sources: [1], [2], [3]
Caveats: Four of the 7 long-term trials had serious reporting flaws, and the authors called the effect's clinical relevance uncertain [2]. The pooled estimates shrink as trial quality rises [3].

Garcinia cambogiaModerate

Weight loss

Mixed results: pooled trials found about 0.9 to 1.3 kg more weight loss than placebo in overweight adults, while the two largest trials found no difference.

The numbers and sources

Effect: Pooling 9 RCTs, weight loss was 0.88 kg greater with hydroxycitric acid than placebo (95% CI -1.75 to -0.00) [1]. A dose-response meta-analysis of 8 trials with 530 subjects found weight 1.34 kg lower (95% CI -2.62 to -0.07) and BMI 0.99 kg/m² lower (95% CI -1.48 to -0.49) than placebo [2]. In the largest single trial, 135 overweight adults on a high-fiber, low-energy diet lost 3.2 kg with 1,500 mg of hydroxycitric acid a day and 4.1 kg with placebo over 12 weeks. The difference was not significant, and fat mass loss did not differ [3]. In 86 overweight adults eating their usual diet, 2 g a day of garcinia extract for 10 weeks did not change weight or body fat compared with placebo [4].
Population: Overweight and obese adults in RCTs [1][2]; 135 adults with BMI about 32 [3]; 86 adults with BMI 23 to 29 in Korea [4].
Sources: [1], [2], [3], [4]
Caveats: The upper bound of the confidence interval in [1] reached zero. The pooled trials were short and the authors of [1] called the clinical relevance uncertain. The two largest controlled trials [3][4] found no difference from placebo.

GlucomannanModerate

Weight loss

Mixed results: one review found about 0.8 kg more weight loss, and a review of overweight and obese adults found no significant difference.

The numbers and sources

Effect: In the 2008 meta-analysis, body weight was 0.79 kg lower with glucomannan (95% CI -1.53 to -0.05) [1]. A 2014 meta-analysis of 8 RCTs restricted to overweight and obese participants found a difference of 0.22 kg that was not significant (95% CI -0.62 to 0.19, I² 65%) [4]. A 2015 systematic review of 6 RCTs found short-term weight reductions at single time points in 3 adult trials and no change in BMI in any trial [5], and its authors later published a correction and reanalysis of data errors [6].
Population: Adults and children in RCTs [1]; overweight and obese adults [4][5].
Sources: [1], [4], [5], [6]
Caveats: Sources disagree. Pediatric patients and people already on dietary changes benefited less in [1]. Only one trial in [5] reported an effect at more than one time point.

Green tea extractModerate

Weight loss

Mixed results: trials outside Japan found no weight change, while Japanese trials and an earlier review found losses of about 0.2 to 3.5 kg.

The numbers and sources

Effect: In 6 studies outside Japan (532 participants), weight change differed from control by -0.04 kg (95% CI -0.5 to 0.4). Eight Japanese studies (1,030 participants) could not be pooled and ranged from -0.2 to -3.5 kg [1]. An earlier meta-analysis of 11 articles found catechins lowered body weight by 1.31 kg, with -0.82 kg in Caucasian and -1.51 kg in Asian participants [2].
Population: Overweight or obese adults in trials of 12 to 13 weeks [1]; weight loss and maintenance studies [2].
Sources: [1], [2]
Caveats: The two reviews disagree. The Cochrane review required at least 12 weeks and analyzed Japanese and non-Japanese trials separately [1].

ProbioticsModerate

Body weight in overweight and obesity

Mixed results: several reviews found about 1.2 kg lower weight with Lactobacillus strains in adults with overweight, while one found no significant change.

The numbers and sources

Effect: Lactiplantibacillus plantarum lowered body weight by 1.23 kg (95% CI 0.49 to 1.97, 18 RCTs, 1,310 adults) [34] and 1.20 kg (95% CI 0.48 to 1.92, 17 RCTs) [35], and waist by 1.36 cm in both. Lactobacillus species lowered weight 1.16 kg (95% CI 0.53 to 1.79, 12 trials, 1,058 people) [36]. A network meta-analysis of 47 studies (3,555 people) found the largest drops, 2.83 and 2.14 kg, with two multi-genus mixes [37]. A 2026 review of 10 RCTs (633 adults) found no significant change in body weight (SMD -0.44, 95% CI -0.92 to 0.04) and a BMI drop that weakened in sensitivity analysis [38].
Population: Adults with overweight or obesity [34][35][36][37][38]. Three reviews excluded people with diabetes or other conditions [34][35][36].
Sources: [34], [35], [36], [37], [38]
Caveats: The reviews disagree on whether weight changes. Effects differ by strain, and certainty ranged from low to high across outcomes [34][37].

Apple cider vinegarLimited

Body weight

Limited evidence: one review found lower weight, but it included a trial later retracted. A larger review found no change in BMI.

The numbers and sources

Effect: In 10 RCTs (789 participants), daily ACV reduced body weight (SMD -0.39, 95% CI -0.63 to -0.15), BMI (SMD -0.65) and waist circumference (SMD -0.34), with no change in other body composition measures [5]. In obese Japanese adults, a drink with 15 or 30 ml of vinegar a day for 12 weeks lowered body weight, BMI, visceral fat and waist circumference compared with placebo [6]. A 2025 meta-analysis of 25 trials found no significant change in BMI [4].
Population: Adults with overweight, obesity or type 2 diabetes [5]. Obese Japanese adults [6]. 1,320 adults in 25 trials [4].
Sources: [5], [6], [4]
Caveats: The 10-trial meta-analysis included a 2024 Lebanese trial [5] that was retracted in September 2025 because its analyses could not be replicated, multiple errors were found, and the dataset showed patterns inconsistent with random allocation [7]. The Japanese trial tested vinegar not specified as apple cider vinegar, and its lead author worked for Mizkan Group, a vinegar maker [6].

Fiber supplementsLimited

Body weight

Limited evidence: soluble fiber lowered weight about 2.5 kg in overweight adults over short trials, while a glucomannan review found no change and a psyllium review reported a gain.

The numbers and sources

Effect: Across 12 RCTs (609 overweight and obese adults) lasting 2 to 17 weeks without calorie restriction, isolated soluble fiber reduced body weight by 2.52 kg (95% CI -4.25 to -0.79), BMI by 0.84 and body fat by 0.41% [6]. Across 11 glucomannan trials, obesity indices did not change significantly [7]. A 2025 meta-analysis of 27 psyllium RCTs in adults reported a significant increase in body weight (weighted mean difference 3.57, 95% CI 1.43 to 5.72) with no change in BMI (-0.06, 95% CI -0.68 to 0.55) or waist circumference [9].
Population: Overweight and obese adults [6]; adults with insulin resistance-related conditions [7]; adults in psyllium RCTs [9].
Sources: [6], [7], [9]
Caveats: Considerable heterogeneity for most outcomes, and short trials [6]. The psyllium review runs opposite in direction to the soluble fiber review, its abstract does not state the unit of the weight estimate, and its BMI estimate did not move with the weight estimate [9].

GABALimited

Growth hormone and lean mass

Small trials found 3 g raised growth hormone in trained men, but 200 mg a day did not change body fat or lean mass in women with obesity.

The numbers and sources

Effect: In 11 resistance-trained men, 3 g of GABA raised peak resting growth hormone about 400% and area under the curve about 375% compared with placebo, and growth hormone was also higher after exercise [7]. In 21 men training twice a week for 12 weeks, 10 g of whey plus 100 mg of GABA increased fat-free mass more than whey alone [8]. In 26 women with obesity training 3 days a week for 90 days, 200 mg of GABA a day did not change body fat, fat mass, fat-free mass or growth hormone compared with placebo. Within the GABA group, BMI and waist circumference fell and sit-up performance rose [9].
Population: 11 men aged 18 to 30, crossover [7]. 21 men aged 26 to 48 [8]. 26 women with obesity [9].
Sources: [7], [8], [9]
Caveats: All three trials were small. The within-group changes in the women's trial were not differences from placebo [9]. The lean mass trial was funded by Pharma Foods International, which supplied the GABA and employed four authors [8]. A rise in growth hormone was not shown to change muscle in [7].

TMGLimited

Body fat

Limited evidence: two reviews disagree. One found about 2.5 kg less fat mass, and a later one found no change in body fat.

The numbers and sources

Effect: One meta-analysis found lower fat mass (-2.53 kg, 95% CI -3.93 to -0.54) and body fat percentage (-2.44%, 95% CI -4.20 to -0.68), with no change in weight or BMI [4]. A later meta-analysis found no change in body mass, BMI, body fat percentage (WMD 0.26%, 95% CI -0.82 to 1.36), fat mass (WMD -0.57 kg, 95% CI -2.14 to 0.99) or fat-free mass [5].
Population: 195 participants in 6 RCTs [4]; studies published up to August 2021 [5].
Sources: [4], [5]
Caveats: The two reviews disagree. One funder of [4] was a research fund supported by DSM, a nutrition ingredient company.

Tart cherryStrong

Blood pressure and cardiometabolic markers

Not shown to change blood pressure, cholesterol or body fat in adults. Fasting glucose and CRP fell very slightly.

The numbers and sources

Effect: Across 10 RCTs, tart cherry juice did not change blood pressure, cholesterol, triglycerides or body fat. Fasting glucose fell by 0.51 mg/dL [4]. Across 21 trials, blood pressure, heart rate, hs-CRP and IL-6 did not change, while CRP fell by 0.39 mg/L (95% CI -0.74 to -0.05, moderate certainty) [5]. A 3-month trial in 50 middle-aged adults found no change in vascular or metabolic measures [6].
Population: Adults across 10 to 21 RCTs [4][5]; middle-aged adults, 30 mL concentrate twice a day [6].
Sources: [4], [5], [6]
Caveats: A 0.51 mg/dL glucose change is very small. The 3-month trial was funded by the Cherry Research Committee [6].

Beta-alanineModerate

Body composition and muscle gain

Not shown to change body mass, fat mass or fat-free mass in adults in training, across 20 trials.

The numbers and sources

Effect: Across 20 RCTs (492 participants), beta-alanine did not change body mass (-0.15 kg, 95% CI -0.78 to 0.47), fat mass (-0.24 kg, 95% CI -1.16 to 0.68), body fat percentage (-0.06%) or fat-free mass (0.05 kg, 95% CI -0.71 to 0.82). Results were the same across training type, duration and dose [7].
Population: Adults in resistance, endurance or combined training [7].
Sources: [7]
Caveats: Certainty ranged from low to moderate. The authors report no funding [7].

GlutamineModerate

Athletic performance and body composition

Not shown to change lean mass, body fat or VO2max in athletes. Body weight fell about 1.4 kg.

The numbers and sources

Effect: Across 25 trials in athletes over 18, glutamine did not change lean body mass, body fat percentage or VO2max. Body weight fell by 1.36 kg (95% CI -2.55 to -0.16) [1].
Population: Athletes, 47 studies reviewed and 25 pooled [1].
Sources: [1]
Caveats: One meta-analysis. The weight change is not explained by a lean mass or fat change in the same analysis [1].

HMBModerate

Fat loss

Not shown to lower fat mass in athletes, young lifters or older adults. One dieting trial that also gave protein found more fat loss.

The numbers and sources

Effect: Fat mass did not change significantly in pooled trials of athletes (ES -0.20) [1], young lifters [2] or older adults [5]. An umbrella review of 11 meta-analyses found no significant change in fat mass (ES 0.03) or body mass, alongside small gains in muscle mass (ES 0.21) and strength (ES 0.27) [12]. In one 12-week trial during calorie restriction, a powder with 3.0 g HMB and 24 g protein a day lowered body fat by 4.9 kg more than a maltodextrin control (95% CI -6.8 to -3.1) and kept skeletal muscle mass 1.3 kg higher [13].
Population: Athletes, young lifters and older adults [1][2][5][12]. 102 Chinese adults with obesity, mean age 36.8 [13].
Sources: [1], [2], [5], [12], [13]
Caveats: The umbrella review [12] pools earlier meta-analyses rather than new trials, and rated 3 of its 11 critically low quality. The dieting trial also gave protein, so the effect of HMB alone cannot be separated [13].

NMNModerate

Insulin sensitivity and metabolic markers

Not shown to change weight, glucose, HbA1c or lipids across trials. One small trial found better insulin sensitivity in women with prediabetes.

The numbers and sources

Effect: In women with prediabetes and overweight or obesity, insulin-stimulated glucose disposal measured by clamp rose after 10 weeks of NMN and did not change on placebo [7]. Across 15 trials, NMN did not change body weight, BMI, fasting glucose, HbA1c or lipids. HOMA-IR showed a downward trend that was not significant [8]. In the 60-day dose trial, HOMA-IR did not differ from placebo [1].
Population: Postmenopausal women with prediabetes [7]; 15 RCTs at 250 to 2,000 mg a day for 14 days to 24 weeks [8]; 80 middle-aged adults [1].
Sources: [7], [8], [1]
Caveats: The clamp result comes from a single small trial in one population [7]. The pooled trials were short [8].

BCAAs and EAAsLimited

Lean mass during dieting

One trial found BCAAs did not significantly reduce lean mass loss over 16 weeks of dieting in 132 adults, and a high-protein diet lost the least.

The numbers and sources

Effect: In 132 adults with overweight or obesity on a 500 kcal daily deficit for 16 weeks, lean mass fell 4.39% with BCAAs (0.1 g per kg a day), 5.39% with placebo and 3.67% with a high-protein diet (p = 0.06). Insulin sensitivity did not differ among groups [6].
Population: 132 Chinese adults aged 21 to 45 [6].
Sources: [6]
Caveats: One RCT. The high-protein diet group lost the least lean mass [6].

GlucomannanLimitedStudied in children

Weight in children

One trial found no change in BMI z score in children with overweight over 12 weeks. Total and LDL cholesterol were lower.

The numbers and sources

Effect: In 96 children aged 6 to 17 with overweight or obesity, 3 g a day for 12 weeks did not change BMI-for-age z score compared with maltodextrin placebo (mean difference 0.0, 95% CI -0.1 to 0.1). Total and LDL cholesterol were lower with glucomannan at 12 weeks [7].
Population: 96 children in Poland [7].
Sources: [7]
Caveats: One trial. It was funded in part by Dicofarm S.p.A. and the Nutricia Foundation, along with the Medical University of Warsaw [7].

Nicotinamide ribosideLimitedStudied in men

Insulin sensitivity and metabolism

One trial found no change in insulin sensitivity, energy expenditure or body composition in men with obesity and insulin resistance.

The numbers and sources

Effect: Over 12 weeks at 2,000 mg a day, NR did not improve insulin sensitivity, glucose production or glucose disposal measured by clamp. Resting energy expenditure, fat oxidation and body composition did not change [7].
Population: 40 sedentary men with obesity and insulin resistance, aged 40 to 70 [7].
Sources: [7]
Caveats: One investigator-initiated trial, in men only [7].

IodineUntested

Metabolism, energy and weight loss

Not studied in people. Iodine is needed to make thyroid hormone, but in mice low iodine shrank fat stores, and in people high intakes went with more underactive thyroid.

No study in people. This rests on how it acts in the body, animal studies.

The numbers and sources

Effect: Iodine is an essential part of the thyroid hormones thyroxine and triiodothyronine, and both too little and too much can cause hypothyroidism or hyperthyroidism [13]. In mice kept on a low-iodine diet, T4 fell and TSH rose, fat made up about 2.3 times more of the energy burned, and fat depots were about 60% smaller than on a normal diet, while oxygen use and activity did not change [14]. In a Chinese cohort, subclinical hypothyroidism developed more often in regions with more than adequate or excessive iodine intake than where intake was mildly deficient [7].
Population: A review [13]. C57BL/6 male mice [14]. 3,018 people in three regions of China [7].
Sources: [13], [14], [7]
Caveats: No trial measured weight, energy or metabolic rate in people given iodine. The mouse result runs opposite to the weight loss claim and does not show what supplements do in people [14].

Raspberry ketonesUntested

Weight loss with raspberry ketone alone

Not studied in people. In mice on a high-fat diet, raspberry ketone limited weight and fat gain, but higher doses killed half or more of obese mice.

No study in people. This rests on animal studies.

The numbers and sources

Effect: In mice fed a high-fat diet with 0.5 to 2% raspberry ketone for 10 weeks, it prevented the rise in body weight, liver weight and visceral fat, and reduced them when added after 6 weeks of high-fat feeding [5]. In obese mice given raspberry ketone for 10 days, weight gain slowed at 165, 330 and 500 mg/kg, but 330 and 500 mg/kg killed 67.6% and 50% of the mice, and ALT and blood glucose rose [6].
Population: Mice on high-fat diets [5][6].
Sources: [5], [6]
Caveats: Mouse studies only. The second study was designed to look for harm, and the deaths occurred at doses that slowed weight gain [6]. No trial of raspberry ketone alone in people was located.

Raspberry ketonesUntested

Metabolic rate

Not studied in people. In the lab, raspberry ketone increased fat breakdown in rat fat cells and raised brown-fat markers in mouse fat cells.

No study in people. This rests on lab studies, how it acts in the body.

The numbers and sources

Effect: Raspberry ketone increased norepinephrine-induced fat breakdown in rat fat cells, with hormone-sensitive lipase moving to the fat droplets [5]. In cultured mouse fat cells, it raised FNDC5 and the brown-fat markers PRDM16, CD137 and UCP1, but did not change irisin released into the medium [7].
Population: Rat epididymal fat cells [5]. Mouse 3T3-L1 fat cells in culture [7].
Sources: [5], [7]
Caveats: Cell studies only. Neither study measured energy expenditure in an animal or a person, and no human study of metabolic rate on raspberry ketone was located.

Practices

Red light therapyModerate

Weight and waist size in obesity

Shown to reduce waist size, weight and BMI in people with obesity in one meta-analysis of 11 trials. Body fat percentage did not change.

The numbers and sources

Effect: Across 11 RCTs (569 patients), photobiomodulation improved waistline (mean difference -7.28, 95% CI -9.97 to -5.67), weight (-3.54, 95% CI -5.97 to -1.11) and BMI (-1.18, 95% CI -1.93 to -0.43), and lowered C-reactive protein, total cholesterol and HOMA-IR. Fat mass percentage (-0.28, 95% CI -1.25 to 0.69), waist-to-hip ratio and insulin did not differ [14].
Population: 569 people with obesity in 11 RCTs with varied comparators, including exercise, diet and sham light [14].
Sources: [14]
Caveats: The abstract does not give units for the mean differences. Comparators varied, and the measure of body fat itself did not change. The authors call for larger multi-center trials with longer follow-up [14].

Cold water immersionLimited

Fat loss and metabolism

Mixed results: metabolic rate rose during cold immersion, and adults ate about 50% more at a meal afterward in one crossover trial. No trial measuring fat loss was located.

The numbers and sources

Effect: Metabolic rate rose by 350% during 1 hour at 14°C and by 93% at 20°C [16]. In 15 adults, energy intake at a meal after 30 minutes in 16°C water was 2,783 kJ, against 1,817 kJ after 35°C water and 1,894 kJ after sitting in air [23]. Experienced winter swimmers showed greater cold-induced thermogenesis than controls, and no brown fat activity at a comfortable temperature [24]. A review of 104 studies concluded cold water immersion seems to reduce or transform body fat, and that small, single-sex studies prevented clear conclusions [25].
Population: Young men [16]. 10 men and 5 women in a randomized crossover [23]. Young men who swim in winter 2 to 3 times a week, combined with sauna, and controls [24]. 104 studies [25].
Sources: [16], [23], [24], [25]
Caveats: Energy burned during immersion was not weighed against the extra food eaten afterward in the same people. Winter swimmers may differ from controls for reasons other than swimming, a point the review also raises [25].

Infrared saunaLimited

Weight loss

Mixed results: a 2009 review found one weak supporting study for obesity, while fat mass rose in the sauna group of a 6-week study in female athletes.

The numbers and sources

Effect: The review described the evidence for obesity as weak and resting on one study [14]. In 40 female athletes training for 6 weeks, body mass and fat mass increased in the group using a post-training infrared sauna, with a group by time interaction for fat mass (p = 0.036) in one statistical model. Body mass rose from 64.8 to 65.7 kg in the sauna group [23].
Population: 9 papers reviewed [14]. 40 female team sport athletes [23].
Sources: [14], [23]
Caveats: The review abstract gives no numbers for the obesity study. The athlete study was pair-matched, in lean young women who were not trying to lose weight [23]. No randomized trial of infrared sauna for weight loss was located.

Whole-body cryotherapyLimited

Weight and abdominal fat

Mixed results: body mass and waist fell after 20 sessions in an uncontrolled study of 37 women, and a scoping review of 8 studies reached no definitive conclusion.

The numbers and sources

Effect: A scoping review of 8 studies in people with obesity described cryotherapy as a promising add-on for abdominal obesity and body mass, and stated that the data fail to reach definitive conclusions [21]. In 19 women with metabolic syndrome and 18 healthy women, body mass, body mass index, waist circumference and total fat mass decreased significantly after 20 daily sessions of 3 minutes at -130°C [22].
Population: 8 studies in people with obesity [21]. 37 postmenopausal women with a mean age of about 61 [22].
Sources: [21], [22]
Caveats: The study of women had no untreated group, and its abstract gives no amounts lost [22].

SaunaLimited

Fat loss

One trial found no added fat loss when a sauna followed exercise for 8 weeks. Body mass lost during a sauna session was studied as fluid to be replaced.

The numbers and sources

Effect: Fat mass changed by -0.6 kg (95% CI -1.9 to 0.7, P = 0.339) with exercise plus sauna compared with exercise alone. Exercise alone lowered fat mass by 1.3 kg against control [3]. In 674 sedentary students, body mass lost over two 10-minute dry sauna sessions rose with body mass index, and the authors used it to estimate the fluid to be replaced [27].
Population: 47 sedentary adults over 8 weeks [3]. 326 women and 348 men aged 19 to 20 in a single visit [27].
Sources: [3], [27]
Caveats: Fat mass was a secondary outcome in a small trial [3]. The student study measured weight change across one visit, not body fat [27].

Daily life

Sleep durationStrong

Weight and obesity

Linked to more new obesity in short sleepers in pooled cohorts. Long sleep was not linked to obesity in one review and weakly linked in another.

Compared with people with normal sleep duration [6]; normal sleepers [3]; people with normal sleep duration [4]

The numbers and sources

Effect: Short sleep was linked to higher odds of later obesity (OR 1.45, 95% CI 1.25 to 1.67), and 1.25 (95% CI 1.14 to 1.38) after removing three studies that drove the heterogeneity. Long sleep was not (OR 1.06, 95% CI 0.98 to 1.15) [6]. Another review found a 38% higher risk of obesity in short sleepers (RR 1.38, 95% CI 1.25 to 1.53) [3], and a third an 8% higher risk in long sleepers (RR 1.08, 95% CI 1.02 to 1.15) [4].
Population: 197,906 participants for short sleep and 164,016 for long sleep in 11 prospective studies [6]. 5,172,710 participants in 153 studies [3]. 5,134,036 participants in 137 cohorts [4].
Sources: [6], [3], [4]
Caveats: Observational. Diet, activity, screen use and mood can affect both sleep and weight, and weight gain itself can disturb sleep. The European subgroup showed no clear link (OR 1.45, 95% CI 0.79 to 2.64) [6].

Daily stepsModerate

Weight in step-count programs

Shown to lower weight by about 1 kg in walking programs built on a step counter, measured mostly before and after in the same people.

Compared with before the program, in the same people [11]; before the program in the same people, and control participants, pooled together [8]; control groups the source does not describe [9]

The numbers and sources

Effect: Across 9 pedometer walking programs without a diet change, weight fell by 1.27 kg from baseline (95% CI -1.85 to -0.70), about 0.05 kg a week, with more loss in longer programs [11]. Pooling all studies, body mass index fell by 0.38 (95% CI 0.05 to 0.72) [8]. Activity tracker reviews reported about 1 kg less body weight [9].
Population: 307 participants in 9 cohorts, 73% women, 4 weeks to 1 year [11]. 2,767 participants in 26 studies [8]. 39 reviews [9].
Sources: [11], [8], [9]
Caveats: Small changes, mostly measured before and after in the same people, with no group left without a counter in most programs [11].

Sitting timeModerate

Long-term programs to cut sitting

Shown to cut sitting by about an hour a day and lower HbA1c 0.17%, body fat and waist size in trials of people with chronic conditions.

Compared with control interventions [9]; control offices whose workers were told to behave as usual [10]

The numbers and sources

Effect: Lifestyle programs cut sedentary time by 64 minutes a day (95% CI -91 to -38). HbA1c fell 0.17% (95% CI -0.30 to -0.04), body fat 0.66 percentage points and waist circumference 1.52 cm against control groups [9]. In office workers, a workplace program cut sitting by 71 minutes per 8-hour workday at 1 month and 48 minutes at 3 months, and body fat was 0.61 percentage points lower at 3 months [10].
Population: 18 randomized trials in people with overweight, type 2 diabetes, heart, neurological or musculoskeletal disease [9]. 317 office workers in 19 offices, cluster randomized [10].
Sources: [9], [10]
Caveats: Programs often added counseling and activity, so the effect of less sitting alone cannot be separated out. Follow-up was months, not years.

Sleep durationModerate

Eating and weight in sleep loss and sleep extension trials

Shown to raise food intake by about 385 kcal a day when sleep was cut. One trial of sleep extension in short sleepers found 270 kcal less eaten daily.

Compared with a control condition with usual sleep [7]; people who kept their habitual sleep [8]

The numbers and sources

Effect: Partial sleep deprivation raised energy intake by 385 kcal a day (95% CI 252 to 517) with no change in total energy expenditure or resting metabolic rate. Fat intake rose and protein intake fell [7]. In adults with overweight who slept under 6.5 hours, sleep hygiene counseling lengthened sleep by about 1.2 hours a night and cut energy intake by 270 kcal a day (95% CI -393 to -147) against controls over 2 weeks. Weight changed by -0.87 kg (95% CI -1.39 to -0.35) relative to controls [8].
Population: 496 participants in 17 studies, 172 in the 11 pooled [7]. 80 adults aged 21 to 40 with a BMI of 25.0 to 29.9 [8].
Sources: [7], [8]
Caveats: The restriction studies lasted days and many were done in a laboratory [7]. The extension result comes from one 2-week trial. Whether the change in intake lasts was not measured [8].

GardeningModerate

Body weight

Mixed results: one meta-analysis of mostly cross-sectional studies linked community gardening to lower body mass index, while a randomized trial found no change in weight or waist.

Compared with non-gardeners, or the same people before gardening [11]; a waiting list for a community garden plot [7]

The numbers and sources

Effect: Pooled body mass index data showed a significant reduction with gardening, larger in quasi-experimental and case-control studies than in cross-sectional ones [11]. In the randomized trial, body mass index and waist circumference did not change over one season [7].
Population: 19 studies, 14 cross-sectional, 4 quasi-experimental and 1 case-control [11]. 291 adults [7].
Sources: [11], [7]
Caveats: The meta-analysis abstract gives no pooled size, and cross-sectional data cannot show that gardening came first [11]. The trial was short for weight change [7].

Screen timeModerateStudied in children

Weight in children's screen-time programs

Not shown to change body mass index in children and teenagers in a meta-analysis of 14 trials, though the programs cut screen time by about 7 hours a week.

Compared with control groups in randomized trials [7]

The numbers and sources

Effect: Screen time programs cut total screen time by 6.90 hours a week (95% CI -9.19 to -4.60) and TV time by 6.17 hours a week. Body mass index and BMI z-score did not differ from control groups [7].
Population: 1,894 children and adolescents in 14 randomized trials [7].
Sources: [7]
Caveats: Programs varied in length and content, and the abstract gives no pooled BMI figure [7].

Food and drink

Added sugarStrong

Body weight, eating less or more sugar

Shown to lower body weight about 0.8 kg when adults ate less sugar, and to raise it as much when they ate more. Swapping sugar for other carbohydrates changed nothing.

Compared with groups eating more sugar, or less, in trials of freely chosen diets [3]; other carbohydrates with the same calories [3]; control groups in trials that cut or added sugar-sweetened drinks [4]

The numbers and sources

Effect: In adults on freely chosen diets, eating less sugar lowered body weight by 0.80 kg (95% CI 0.39 to 1.21) and eating more raised it by 0.75 kg (95% CI 0.30 to 1.19). Exchanging sugars for other carbohydrates with the same calories did not change weight (0.04 kg, 95% CI -0.04 to 0.13). Trials advising children to cut sugar had low compliance and found no overall weight change [3]. Adding sugar-sweetened drinks raised adult body weight by 0.85 kg (95% CI 0.50 to 1.20). Cutting them in children reduced BMI gain by 0.17 units (random effects 95% CI -0.39 to 0.05, fixed effects significant) [4]. In cohorts, the highest intake of sugar-sweetened drinks was linked to 55% higher odds of overweight after a year [3].
Population: 30 trials and 38 cohort studies in adults and children [3]. 5 trials in 2,772 children and 5 trials in 292 adults, plus 22 cohorts [4].
Sources: [3], [4]
Caveats: The weight change came from calories, since equal-calorie swaps changed nothing [3]. Trials were short, and the children's result depends on the statistical model used [4].

Non-sugar sweetenersStrong

Body weight, in place of sugar

Shown to lower body weight by about 1 kg when sweetened foods or drinks replaced sugar-sweetened ones, in pooled trials of adults.

Compared with sugar-sweetened drinks [5]; sugar-sweetened foods or drinks [6]; the regular-calorie versions of the same foods and drinks [7]

The numbers and sources

Effect: Replacing sugar-sweetened drinks with low- and no-calorie sweetened drinks lowered body weight by 1.06 kg (95% CI -1.71 to -0.41), BMI by 0.32 and body fat by 0.60 percentage points, with moderate certainty [5]. In sustained trials of 4 weeks to 40 months, sweeteners against sugar lowered body weight by 1.35 kg (95% CI -2.28 to -0.42), and before a meal cut total energy intake by 94 kcal [6]. Across 15 trials, low-calorie sweeteners lowered weight by 0.80 kg (95% CI -1.17 to -0.43), fat mass by 1.10 kg and waist by 0.83 cm [7]. In children, sweeteners against sugar gave a smaller rise in BMI z score (-0.15, 95% CI -0.17 to -0.12) and no significant difference in weight [8].
Population: 601 adults with overweight or obesity, at risk for or with diabetes, in 12 trials [5]. 9 sustained trial comparisons [6]. 15 trials [7]. 528 children in 2 studies [8].
Sources: [5], [6], [7], [8]
Caveats: The weight differences are small. WHO's 2023 review, the basis of its guideline, found no long-term benefit in reducing body fat [1].

Green teaLimited

Weight and waist size

One small trial found a larger drop in waist size with a catechin-rich green tea drink than a low-catechin one, in people with type 2 diabetes.

Compared with a green tea drink with 96.3 mg of catechins a day [8]

The numbers and sources

Effect: After 12 weeks, waist circumference fell more with 582.8 mg of catechins a day than with 96.3 mg, and adiponectin rose only in the high-catechin group [8].
Population: 23 adults on the catechin-rich drink and 20 on the control drink, all with type 2 diabetes [8].
Sources: [8]
Caveats: One small double-blind trial of a drink richer in catechins than brewed tea. The abstract gives no weight change. Pooled weight-loss trials, mostly of extracts, are on the green tea extract page.

DairyStrong

Body weight

Mixed results: trials found no weight change from adding dairy without cutting calories, and 1.2 to 1.3 kg more weight loss when dairy was part of calorie-restricted diets.

Compared with control diets lower in dairy [6][8]; usual weight loss diets with less dairy [7]; 200 g a day less dairy, in a dose-response model of cohorts [9]

The numbers and sources

Effect: Across 29 trials, dairy did not change body weight overall (-0.14 kg, 95% CI -0.66 to 0.38, I² 86.3%) and modestly reduced body fat (-0.45 kg, 95% CI -0.79 to -0.11). Weight fell in energy-restricted or short trials, and rose in trials without energy restriction or lasting a year or more [6]. Without energy restriction, more dairy did not significantly change weight, fat or waist size, while high-dairy weight loss diets gave 1.29 kg more weight loss (95% CI -1.98 to -0.60) [7]. In energy-restricted trials in adults aged 18 to 50, mostly women, 2 to 4 servings a day gave 1.16 kg more weight loss (95% CI -1.66 to -0.66) and less loss of lean mass [8]. In cohorts, overweight or obesity was 25% lower per extra 200 g a day of total dairy [9].
Population: 2,101 adults in 29 trials [6]. 14 trials [7]. 27 trials, median 16 weeks, 90% women [8]. Cohort studies [9].
Sources: [6], [7], [8], [9]
Caveats: Heterogeneity was high [6]. The calorie-restricted results come largely from women [8]. Cohort links are observational.

Non-sugar sweetenersModerate

Body weight, against water or no sweetener

Mixed results: against water, one review found no weight difference and another 1.24 kg less, while trials against no sweetener found little or no change.

Compared with water [5][6]; no or lower sweetener intake [8]; control groups the abstract does not describe [9]

The numbers and sources

Effect: Replacing water with sweetened drinks was not associated with body weight, with low certainty [5]. In 3 sustained trial comparisons against water, sweeteners lowered weight by 1.24 kg (95% CI -2.22 to -0.26), and before a meal energy intake did not differ (-2 kcal) [6]. In adults, a small BMI fall (-0.6, 95% CI -1.19 to -0.01) came from 2 studies of 174 people, and no effect was seen in people actively trying to lose weight [8]. In 7 trials, sweeteners did not significantly change BMI (-0.37, 95% CI -1.10 to 0.36) [9].
Population: 974 adults in 9 trials of sweetened drinks against water [5]. 3 trial comparisons [6]. Small trials in adults and children [8]. 1,003 participants in 7 trials, median 6 months [9].
Sources: [5], [6], [8], [9]
Caveats: Few trials, mostly small and short [8][9]. Certainty for the water comparison was low [5].

NutsStrong

Body weight

Not shown to change body weight, body mass index or waist size in two meta-analyses of nut-feeding trials, either up or down.

Compared with control diets [9]; control groups the abstract does not describe [10]

The numbers and sources

Effect: Across 33 trials, diets with nuts did not differ from control diets in body weight (WMD -0.47 kg, 95% CI -1.17 to 0.22), BMI or waist circumference [9]. Across 55 trials, body weight did not change with or without instructions to swap nuts for other foods. Body fat percentage fell slightly when swap instructions were given (SMD -0.32, 95% CI -0.61 to -0.03) [10].
Population: 33 randomized trials [9]. Adults in 55 trials lasting more than 3 weeks [10].
Sources: [9], [10]
Caveats: Trials were short. Many included instructions to replace other foods with nuts, which is not the same as adding nuts on top of a usual diet [10].

Fermented foodsModerate

Body weight

Not shown to change body weight or body measurements in a meta-analysis of kefir trials. Kimchi cohorts linked higher intake to normal body weight.

Compared with control groups [7]; people eating less kimchi [9]

The numbers and sources

Effect: Kefir had no significant effect on anthropometric measures [7]. Prospective cohorts linked higher kimchi intake with a greater likelihood of normal body weight [9].
Population: 24 kefir studies [7]. 42,455 participants in 4 kimchi cohorts [9].
Sources: [7], [9]
Caveats: The kefir abstract gives no size for the weight result. The kimchi finding is observational.

GrapefruitModerate

Body weight

Not shown to lower body weight in overweight adults in one meta-analysis of 3 trials. One trial found 1.3 kg more loss with fresh grapefruit than placebo.

Compared with control groups in 3 randomized trials [2]; placebo capsules with apple juice [3]; a control diet low in fruits and vegetables [4]; a water preload matched for weight and calories [5]

The numbers and sources

Effect: Across 3 randomized trials with 250 participants, weight change did not differ between grapefruit and controls (MD -0.45 kg, 95% CI -1.06 to 0.16, I² 53%) [2]. In one of them, after 12 weeks the fresh grapefruit group lost 1.6 kg, the grapefruit juice group 1.5 kg, the grapefruit capsule group 1.1 kg and the placebo group 0.3 kg. The fresh grapefruit group lost significantly more than placebo (P < .05) [3]. Half a grapefruit with each meal for 6 weeks did not change weight against a control diet, with a change of -0.61 kg from baseline (P = .097) [4]. In 85 obese adults on calorie restriction, weight fell 7.1% overall over 12 weeks, with no difference between grapefruit, grapefruit juice and water preloads [5].
Population: 250 overweight and obese adults in 3 trials [2]. 91 obese adults for 12 weeks [3]. 74 overweight adults for 6 weeks [4]. 85 obese adults for 12 weeks [5].
Sources: [2], [3], [4], [5]
Caveats: Few trials, all short, and the reviewers note no established minimum dose [2]. The water preload trial matched preloads for calories, so it tested grapefruit against another low-energy food, not against eating nothing [5].

Whole grainsModerate

Body weight

Not shown to change body weight in pooled trials against non-whole-grain foods. Body fat was 0.48 percentage points lower.

Compared with non-whole-grain control foods [13]

The numbers and sources

Effect: Whole grain intake did not change body weight (0.06 kg, 95% CI -0.09 to 0.20) and lowered body fat percentage slightly (-0.48%, 95% CI -0.95 to -0.01). The whole grain dose did not predict the difference [13].
Population: 2,060 apparently healthy adults in 26 randomized trials of up to 16 weeks [13].
Sources: [13]
Caveats: Trials were short, which the authors say may explain the lack of difference [13].

Diets

Alternate-day fastingStrong

Weight loss compared with usual eating

Shown to lower weight, BMI and fat mass against control in adults with overweight, by about 1.3 kg of fat mass, mostly in trials under 6 months.

Compared with eating every day, with no fasting days or daily fasting window

The numbers and sources

Effect: In 8 trials with 728 participants, BMI fell 0.73 kg/m² (95% CI -1.13 to -0.34) and fat mass 1.27 kg (95% CI -2.09 to -0.46) against control, with significant effects in participants with overweight and in trials under 6 months [1]. In 7 trials with 269 participants, weight, BMI and fat mass fell against control (weight p below 0.00001) [2]. In a year-long trial, weight fell 6.0% (95% CI -8.5% to -3.6%) against no intervention [3]. In healthy non-obese adults, 4 weeks of strict alternate-day fasting cut calorie intake 37% and lowered fat mass, mostly trunk fat [4]. In adults with BMI 23 to 30, total fat volume fell 1,059.8 cm³ more than in controls over 4 weeks (95% CI -1,380.0 to -739.6) [5].
Population: Adults aged 18 and over in 8 trials [1]; 269 adults in 7 trials [2]; 100 adults with obesity, 86 women [3]; healthy middle-aged adults without obesity [4]; 76 adults aged 18 to 40 [5].
Sources: [1], [2], [3], [4], [5]
Caveats: The pooled effects held for trials under 6 months [1]. The reviews are small, and [2] reports p values without effect sizes.

High-protein dietStrong

Fat loss and body weight

Shown to lower body weight and fat mass slightly more than standard-protein diets, by about 0.6 to 0.9 kg of fat.

Compared with diets with less protein

The numbers and sources

Effect: On isocaloric energy-restricted diets, high protein lowered weight 0.79 kg more (95% CI 0.08 to 1.50) and fat mass 0.87 kg more (95% CI 0.48 to 1.26) [1]. Across 74 trials, higher-protein diets favored weight loss (SMD -0.36, 95% CI -0.56 to -0.17) and waist circumference (SMD -0.43, 95% CI -0.69 to -0.16) [6]. Fat mass fell 0.64 kg more (95% CI 0.29 to 0.98) [3]. In adults without kidney disease, high-protein diets lowered body fat percentage and total fat mass [5].
Population: Adults in weight-loss trials [1][3]; 74 trials of higher against lower protein [6]; 22 RCTs in adults without chronic kidney disease [5].
Sources: [1], [3], [5], [6]
Caveats: The differences are under 1 kg [1][3]. Most trials were short, a mean of 12.1 weeks in [1].

Intermittent fastingStrong

Weight loss compared with usual eating

Shown to lower body weight against usual eating in adults, by about 1.6 kg in pooled trials, though one 12-week trial without other changes found no difference.

Compared with no intervention or a waiting list [1]; eating over 10 or more hours a day [4]; no restriction [7]; usual diets, and late time-restricted eating for the early-window result [8]; three structured meals a day [9]

The numbers and sources

Effect: Against no intervention or a waiting list, percentage weight loss differed by -3.42 points (95% CI -4.95 to -1.90, 6 studies, 427 participants, moderate certainty) [1]. Time-restricted eating alone lowered weight by 1.59 kg (95% CI -2.02 to -1.15) and fat mass by 0.93 kg (95% CI -1.22 to -0.63) against no restriction [7]. In 41 trials with 2,287 participants, time-restricted eating lowered body weight, BMI, fat mass and waist circumference against usual diets, and early windows lost 1.15 kg more than late windows (95% CI -1.86 to -0.45, high certainty) [8]. An 8-hour window lost 4.61 kg more than control at 12 months (95% CI -7.37 to -1.85) [4]. In the 12-week TREAT trial, a noon to 8 p.m. window and three structured meals a day differed by -0.26 kg (95% CI -1.30 to 0.78, P .63) [9].
Population: Adults with overweight or obesity [1]; 20 trials with 1,242 adults [7]; 41 trials with 2,287 participants [8]; 90 adults with obesity [4]; 116 adults aged 18 to 64 with BMI 27 to 43 [9].
Sources: [1], [4], [7], [8], [9]
Caveats: The Cochrane authors describe the -3.42 point difference as likely little to no difference [1]. In the 12-month trial, calorie intake fell 425 kcal a day on the 8-hour window, close to the 405 kcal fall on calorie restriction [4]. Early eating windows ended before 5 p.m. [8].

Keto dietStrong

Weight loss

Shown to produce about 1 to 3 kg more weight loss than comparison diets in adults, with the smallest gap in trials of a year or longer.

Compared with diets that did not restrict carbohydrates to the level of ketosis

The numbers and sources

Effect: In 13 trials with 12 months or more of follow-up, ketogenic diets lowered weight 0.91 kg more than low-fat diets (95% CI 0.17 to 1.65, 1,415 patients) [1]. Across 27 RCTs (1,278 participants), weight fell 2.59 kg more than on control diets (95% CI 1.28 to 3.90, I² 87.4%) [2]. When prescribed energy was matched, the gap was 1.49 kg (95% CI 0.58 to 2.41, 6 trials, 259 participants) [3]. In type 2 diabetes, weight fell 2.91 kg more at 3 months and 2.84 kg more at 6 months, and the difference was gone at 12 months [4].
Population: Adults, mostly with overweight or obesity [1][2][3]; 648 adults with type 2 diabetes in 8 RCTs [4].
Sources: [1], [2], [3], [4]
Caveats: Heterogeneity was high in [2]. Certainty was low in the energy-matched review, and in its 3 protein-matched trials the effect was imprecise and compatible with no difference [3]. Weight loss certainty in type 2 diabetes was low [4]. The comparison diets varied from low-fat to usual care.

Low-carb dietStrong

Weight loss

Shown to produce about 1 kg more weight loss than balanced-carbohydrate or low-fat diets in adults with overweight, a gap a Cochrane review calls little to no difference.

Compared with balanced-carbohydrate diets [1]; low-fat diets [2]; no diet, and low-fat diets in the same network meta-analysis [3]; a healthy low-fat diet [4]; a calorie-restricted low-fat diet and a calorie-restricted Mediterranean diet [5]

The numbers and sources

Effect: In adults without type 2 diabetes, weight fell 1.07 kg more than on balanced-carbohydrate diets over 3 to 8.5 months (95% CI 0.59 to 1.55, 37 RCTs, 3,286 participants) and 0.93 kg more over 1 to 2 years (95% CI 0.04 to 1.81, 14 RCTs, 1,805 participants). In adults with type 2 diabetes the differences were 1.26 kg at 3 to 6 months and 0.33 kg at 1 to 2 years (95% CI -1.46 to 2.13) [1]. Against low-fat diets in weight-loss trials of a year or more, weight fell 1.15 kg more (95% CI 0.52 to 1.79, 18 comparisons, I² 10%) [2]. Against no diet, low-carbohydrate diets lowered weight 8.73 kg at 6 months and 7.25 kg at 12 months, and low-fat diets 7.99 kg and 7.27 kg [3]. In a 12-month trial, weight fell 6.0 kg on a low-carbohydrate diet and 5.3 kg on a low-fat diet, a difference of 0.7 kg (95% CI -0.2 to 1.6) [4]. In a 2-year trial, mean loss was 4.7 kg low-carbohydrate, 4.4 kg Mediterranean and 2.9 kg low-fat [5].
Population: 6,925 adults with overweight or obesity in 61 RCTs, with and without type 2 diabetes [1]; 53 trials with 68,128 participants [2]; 7,286 adults in 48 trials [3]; 609 adults aged 18 to 50 without diabetes [4]; 322 adults with moderate obesity, 86% men [5].
Sources: [1], [2], [3], [4], [5]
Caveats: Risk of bias across the Cochrane trials was mostly high, from missing outcome data, and certainty was moderate [1]. The difference between diet types is small next to the loss on either diet [3]. In the 2-year trial, the low-carbohydrate arm had no calorie limit and the other two did [5].

Paleo dietStrong

Weight loss

Shown to produce about 2 to 3.5 kg more weight loss than comparison diets in adults, with the fat-loss lead not significant at 2 years in one trial.

Compared with control diets the source does not describe [1]; diets based on official recommendations, mostly higher in vegetables, whole grains and low-fat dairy [2]; control diets the source does not describe [3]; a diet following the Nordic Nutrition Recommendations [4]

The numbers and sources

Effect: In 8 RCTs, weight fell 2.17 kg more than on control diets (95% CI 0.87 to 3.48), with waist 2.90 cm and body fat 1.38 points lower [1]. In 11 randomized studies, weight fell 3.52 kg more than on diets based on official recommendations (95% CI 1.79 to 5.26, I² 24%) [2]. In 19 RCTs, weight fell 1.74 kg more (95% CI 0.91 to 2.57) [3]. In a 2-year trial, fat mass fell 6.5 kg against 2.6 kg on a Nordic guideline diet at 6 months (p < 0.001), and 4.6 kg against 2.9 kg at 24 months (p 0.095) [4].
Population: Adults with and without chronic disease [1][2][3]; 70 postmenopausal women with obesity, mean age 60 [4].
Sources: [1], [2], [3], [4]
Caveats: Most trials were small and short [2]. In the 2-year trial, adherence to the protein target was poor [4].

Vegan dietStrong

Weight

Shown to lower weight about 2.5 to 4 kg against control diets in adults, most in adults with overweight or type 2 diabetes.

Compared with the participants' habitual diet, unchanged, in 3 trials in US and New Zealand adults, and in 8 trials a National Cholesterol Education Program diet, American Diabetes Association and Korean Diabetes Association diets, a portion-controlled diet, a Mediterranean diet, a low-fat diet, a healthy omnivorous diet or a high-carbohydrate lacto-ovo vegetarian diet [1]; non-vegetarian diets [2]

The numbers and sources

Effect: In 11 trials of 12 weeks or more (796 participants), vegan diets lowered weight by 4.1 kg against control diets (95% CI -5.9 to -2.4) and BMI by 1.38 [1]. In a meta-analysis of 12 RCTs, the vegan subgroup lost 2.52 kg more than non-vegetarian diets (95% CI -3.02 to -1.98) [2].
Population: Adults with overweight or type 2 diabetes [1]; adults in RCTs, median 18 weeks [2].
Sources: [1], [2]
Caveats: Part of the effect may reflect lower energy intake and different macronutrients on the vegan diets [1]. Weight loss in vegetarian trials shrank at a year or more [2].

5:2 dietModerate

Weight loss compared with no diet or brief advice

Shown to lower body weight against control diets in adults with overweight or obesity. As one-off self-help instructions, it matched standard brief advice at one year.

Compared with a daily energy-restricted diet or a routine diet [7]; standard brief weight-management advice [8]

The numbers and sources

Effect: In 20 articles with 1,393 participants, 5:2 lowered body weight, BMI, waist circumference, body fat percentage, fat mass, fat-free mass, LDL cholesterol, systolic blood pressure and HOMA-IR against control groups. Visceral fat, total cholesterol, triglycerides, HDL, diastolic pressure, fasting glucose and HbA1c did not differ [7]. One-off 5:2 self-help instructions lost 1.9 kg at one year against 1.8 kg with standard brief advice (p 0.79), and 18% against 15% lost at least 5% of body weight [8].
Population: Adults with overweight or obesity in 20 trials [7]; 300 UK adults with obesity followed for one year [8].
Sources: [7], [8]
Caveats: The meta-analysis abstract reports significance without effect sizes [7]. Adherence to self-help 5:2 fell over the year [8].

DASH dietModerate

Weight

Shown to lower weight about 1.4 kg more than control diets over 8 to 24 weeks in adults, more in people with overweight or obesity.

Compared with weight-loss, low-fat and usual diets, behavioral programs alone, general heart-failure advice and standard low-sodium blood pressure advice [7]; typical Western or usual diets and other low-energy diets [8]

The numbers and sources

Effect: In 10 trials, adults on DASH lost 1.42 kg more than controls (95% CI -2.03 to -0.82) over 8 to 24 weeks, with BMI down 0.42 and waist down 1.05 cm. Lower-calorie DASH lost more than other low-calorie diets [8]. An umbrella review reported the same weight figure [7].
Population: Adults in 13 trials, with larger effects in those with overweight or obesity [8].
Sources: [7], [8]
Caveats: One meta-analysis supplies the figure, which the umbrella review repeated [7][8]. Trials were short.

High-protein dietModerate

Fullness

Shown to raise fullness ratings after higher-protein meals in tightly controlled preload studies of healthy adults.

Compared with diets with less protein

The numbers and sources

Effect: In 5 preload studies, higher-protein preloads raised fullness over 2 to 4 hours more than lower-protein preloads (2,435.74 mm·240 min, 95% CI 1,375.18 to 3,496.31). A directional count of 28 studies also favored higher protein [7]. In weight-loss trials, 3 of 5 studies reported greater satiety with high protein [1].
Population: Healthy adults given intact protein by mouth [7]; adults in weight-loss trials [1].
Sources: [1], [7]
Caveats: The authors caution against extending these results to everyday eating, body weight or health outcomes [7].

Low-fat dietModerate

Body weight without trying to lose weight

Shown to lower body weight about 1.4 kg against higher-fat diets in adults not trying to lose weight, with larger drops at higher starting BMI.

Compared with diets with more fat

The numbers and sources

Effect: Across 37 RCTs (57,079 participants) lasting at least 6 months, eating less fat lowered body weight 1.4 kg against higher fat intake (95% CI 1.1 to 1.7, 26 RCTs, 53,875 participants, I² 75%), BMI 0.5 kg/m² and waist 0.5 cm. Greater fat reduction, lower baseline fat intake and higher baseline BMI went with larger losses [1]. In postmenopausal women given no weight or calorie goals, the low-fat group lost 2.2 kg in the first year and stayed lighter than controls, by 1.9 kg at 1 year and 0.4 kg at 7.5 years [2].
Population: Adults randomized to lower or higher fat intake with no weight-loss aim [1]; 48,835 postmenopausal women aged 50 to 79 in the US, 19,541 in the low-fat group [2].
Sources: [1], [2]
Caveats: Heterogeneity was high, and the review explains it by the size of the fat reduction and baseline BMI [1]. The women's trial also raised vegetables, fruit and grains, so fat was not the only change [2].

Mediterranean dietModerate

Weight

Shown to lower weight about 1.75 kg against control diets in adults, more with calorie restriction or exercise, and to match low-carbohydrate and diabetes association diets.

Compared with control diets the source does not describe [6]; a low-fat diet, a low-carbohydrate diet and the American Diabetes Association diet [7]; a control diet of advice to reduce dietary fat, in Spanish adults [8]; ad libitum Mediterranean diet advice, so both groups ate a Mediterranean diet [9]

The numbers and sources

Effect: Across 16 RCTs (3,436 participants), the Mediterranean diet lowered weight by 1.75 kg against control diets (95% CI -2.86 to -0.64). The difference was 3.88 kg with energy restriction, 4.01 kg with more physical activity and 2.69 kg with follow-up past 6 months [6]. In 5 RCTs lasting 12 months or more (998 participants), mean weight change ranged from 4.1 to 10.1 kg lost on the Mediterranean diet against a range from 2.9 kg gained to 5.0 kg lost on low-fat diets, and weight loss was similar to low-carbohydrate and American Diabetes Association diets [7]. In PREDIMED, with no calorie limit, the 5-year weight change did not differ from the low-fat control (olive oil -0.41 kg, 95% CI -0.83 to 0.01, nuts -0.02 kg, 95% CI -0.45 to 0.42) [8]. In PREDIMED-Plus, an energy-reduced Mediterranean diet with exercise and behavioral support lost 3.2 kg at 12 months against 0.7 kg on ad libitum Mediterranean advice (difference -2.5 kg, 95% CI -3.1 to -1.9) [9].
Population: Adults in 16 trials [6]; adults with overweight or obesity trying to lose weight [7]; older Spanish adults at high cardiovascular risk [8]; 626 adults aged 55 to 75 with overweight or obesity and metabolic syndrome [9].
Sources: [6], [7], [8], [9]
Caveats: The added weight loss in [6] grew when calories were cut or exercise was added, so the diet alone accounts for part of it. In PREDIMED-Plus both groups ate a Mediterranean diet, so the difference reflects calorie reduction, exercise and support [9].

Nordic dietModerate

Weight

Shown to lower weight about 1.8 kg more than control diets in adults, without calorie limits in the trials that supplied food.

Compared with the participants' usual Western diet, in Swedish adults [3]; an average Nordic diet with the same calories [4]; an average Danish diet, with all food supplied free [5]; control groups the source does not describe [6]

The numbers and sources

Effect: In 5 trials reporting weight (7 trials, 774 participants overall), people on a Nordic diet lost 1.83 kg more than controls (95% CI -2.94 to -0.73) [6]. In a 26-week Danish trial with all food supplied free and without calorie limits, weight fell 4.7 kg against 1.5 kg on an average Danish diet (intention-to-treat difference -3.0 kg, 95% CI -4.0 to -2.1) [5]. Weight fell 4% more than controls over 6 weeks in NORDIET [3]. Weight stayed stable in SYSDIET, where calories were matched by design [4].
Population: Adults in Nordic countries [6]; 181 Danish adults aged 20 to 66 with central obesity [5]; adults with mild high cholesterol [3].
Sources: [3], [4], [5], [6]
Caveats: One meta-analysis with few trials, all from Nordic countries. The authors call for trials in other populations [6].

Vegetarian dietModerate

Weight

Shown to lower weight about 2 to 3 kg against non-vegetarian diets in adults. The lacto-ovo subgroup alone did not reach significance.

Compared with control diets the source does not describe [2]; non-vegetarian diets [5]; untreated control groups, which 4 of the 15 trials had [6]

The numbers and sources

Effect: In 12 RCTs (1,151 participants, median 18 weeks), vegetarian diets lowered weight by 2.02 kg against non-vegetarian diets (95% CI -2.80 to -1.23). The vegan subgroup lost 2.52 kg, and the lacto-ovo subgroup 1.48 kg (95% CI -3.43 to 0.47) [5]. A review of 15 trials of vegetarian diets without calorie limits, 4 of them with untreated control groups, estimated weight change against those controls at -3.4 kg by intention to treat (95% CI -4.4 to -2.4) [6]. In adults with diabetes, weight fell 2.15 kg [2].
Population: Adults in RCTs [5]; adults in 15 intervention trials, 4 with untreated controls [6]; adults with diabetes [2].
Sources: [2], [5], [6]
Caveats: Weight loss shrank at a year or more (-1.13 kg) [5]. Only 4 of the 15 trials in [6] had untreated controls.

Carnivore dietLimited

Weight loss

Limited evidence: in a self-report survey of 2,029 adults on the diet, median BMI fell from 27.2 to 24.3.

Compared with before the diet, in the same people [1]

The numbers and sources

Effect: Respondents reported a median BMI of 27.2 (IQR 23.5 to 31.9) before the diet and 24.3 (IQR 22.1 to 27.0) on it [1].
Population: 2,029 adults recruited through social media, median age 44, 67% men, on the diet for a median of 14 months. Survey data, not a trial [1].
Sources: [1]
Caveats: Self-reported and self-selected, with no comparison group. The survey included only people on the diet for 6 months or more [1]. A scoping review of 9 human studies rated the overall evidence very limited, with small samples, short durations and no control groups [2].

One meal a dayLimited

Weight and fat mass

Small crossover trials found one daily meal lowered fat mass against three meals at the same calories, in normal-weight adults over 11 days to 8 weeks.

Compared with eating every day, with no fasting days or daily fasting window

The numbers and sources

Effect: Eating all maintenance calories in one meal a day for 8 weeks reduced fat mass against three meals a day, with body weight kept within 2 kg [1]. Over 11 days, one evening meal lowered body mass 1.4 kg against 0.5 kg on three meals (p 0.03) and fat mass 0.7 kg against 0.1 kg (p 0.049) [2].
Population: Healthy normal-weight middle-aged adults in a randomized crossover trial with two 8-week periods [1]; 13 lean adults enrolled and 11 completed, mean age 31 and BMI 24 [2].
Sources: [1], [2]
Caveats: Very small, short trials in lean adults. The abstract of [1] gives no participant number or size of the fat loss. No trial of one meal a day in people with overweight or obesity was located.

Alternate-day fastingModerate

Weight loss compared with daily calorie restriction

Mixed results: alternate-day fasting lost about 1.3 kg more than daily calorie restriction in pooled trials, mostly short ones, and longer trials found no difference or a small one.

Compared with daily calorie restriction or no intervention, in Chicago adults with obesity [3]; time-restricted eating or no change in eating times [5]; continuous energy restriction, unrestricted eating, time-restricted eating and whole-day fasting [6]; continuous calorie restriction, the 5:2 diet and time-restricted eating [7]; daily calorie restriction with the same weekly deficit, both within a behavioral weight-loss program [8]; a calorie-restricted Mediterranean diet [9]

The numbers and sources

Effect: Against continuous energy restriction, alternate-day fasting lowered weight by 1.29 kg (95% CI -1.99 to -0.59, moderate certainty). In trials of 24 weeks or longer, only comparisons against unrestricted eating showed a benefit [6]. A network analysis of 24 trials ranked alternate-day fasting first for weight loss, while intermittent fasting overall matched continuous restriction [7]. Over one year, weight fell 6.0% on alternate-day fasting and 5.3% on daily restriction against control, with no difference between them [3]. A 4:3 schedule lost 2.89 kg more than daily restriction at 12 months (95% CI 0.14 to 5.65) within a high-intensity behavioral program [8]. Over 3 months of calorie-restricted diets, modified alternate-day fasting lost 3.14 kg more than a Mediterranean diet (95% CI -4.98 to -1.30) [9]. Alternate-day fasting cut fat volume 695.7 cm³ more than time-restricted eating over 4 weeks [5].
Population: 99 trials with 6,582 adults [6]; 24 trials with 1,768 people [7]; 100 adults with obesity [3]; 165 adults with BMI 27 to 46 [8]; 160 adults with obesity [9]; 76 adults without obesity [5].
Sources: [3], [5], [6], [7], [8], [9]
Caveats: The 4:3 schedule restricts 3 non-consecutive days a week, not every other day [8]. In the year-long trial, people on alternate-day fasting ate more than prescribed on fast days and less on feast days [3].

Atkins dietModerate

Weight loss

Mixed results: Atkins produced more weight loss than Zone in one trial and similar loss to other popular diets in another, with gaps shrinking by 12 months.

Compared with the Zone, LEARN and Ornish diets [7]; the Zone, Weight Watchers and Ornish diets [8]; a conventional low-calorie, high-carbohydrate, low-fat diet [9]; the Zone diet and other named diet programs [10]; a high-carbohydrate, high-fibre diet and the high-protein Zone diet [11]

The numbers and sources

Effect: At 12 months, women lost 4.7 kg on Atkins (95% CI 3.1 to 6.3), 1.6 kg on Zone, 2.6 kg on LEARN and 2.2 kg on Ornish, and only the Atkins and Zone difference was significant [7]. In another 1-year trial, mean loss was 2.1 kg on Atkins, 3.2 kg on Zone, 3.0 kg on Weight Watchers and 3.3 kg on Ornish, and weight loss tracked self-reported adherence (r 0.60), not diet type (r 0.07) [8]. Against a conventional low-fat diet, Atkins produced more loss at 3 months (6.8% against 2.7% of body weight) and 6 months (7.0% against 3.2%), and the 12-month difference (4.4% against 2.5%) was not significant [9]. In a network meta-analysis, Atkins produced 1.71 kg more loss than Zone at 6 months, and differences between named diets were minimal [10]. In insulin-resistant women, Atkins produced 2.8 kg more loss than a high-carbohydrate diet [11].
Population: 311 premenopausal women with overweight or obesity [7]; 160 adults aged 22 to 72 with hypertension, dyslipidemia or high fasting glucose [8]; 63 adults with obesity [9]; 7,286 adults in 48 trials [10]; 96 insulin-resistant women [11].
Sources: [7], [8], [9], [10], [11]
Caveats: Adherence was poor and dropout high in several trials [8][9]. Most trials ran 12 months or less.

Intermittent fastingStrong

Weight loss compared with daily calorie restriction

Not shown to cause more weight loss than daily calorie restriction or regular diet advice in adults with overweight or obesity, in trials of up to 12 months.

Compared with regular dietary advice [1]; continuous energy restriction, and time-restricted eating as another fasting form [2]; daily calorie restriction alone [3]; 25% daily calorie restriction [4]

The numbers and sources

Effect: Against regular dietary advice, intermittent fasting changed percentage weight loss by -0.33 points (95% CI -0.92 to 0.26, 21 studies, 1,430 participants, low certainty), and the chance of losing 5% of body weight did not differ (RR 0.98, 95% CI 0.82 to 1.18) [1]. In a network meta-analysis of 99 trials, alternate-day fasting was the only form to lose more weight than continuous energy restriction (-1.29 kg, 95% CI -1.99 to -0.59), and alternate-day fasting lost 1.69 kg more than time-restricted eating [2]. Eating only from 8 a.m. to 4 p.m. on a calorie-restricted diet lost 8.0 kg at 12 months against 6.3 kg on calorie restriction alone, a net difference of -1.8 kg (95% CI -4.0 to 0.4, P 0.11) [3]. An 8-hour window without calorie counting and 25% daily calorie restriction differed by 0.81 kg at 12 months (95% CI -3.07 to 4.69) [4].
Population: 22 randomized trials with 1,995 adults with overweight or obesity, published 2016 to 2024 [1]; 99 trials with 6,582 adults, most with existing health conditions [2]; 139 adults with obesity in China, 118 completing 12 months [3]; 90 adults with obesity in Chicago, 33% Black and 46% Hispanic [4].
Sources: [1], [2], [3], [4]
Caveats: Follow-up in the Cochrane review was 12 months or less [1]. In the network meta-analysis, trials of 24 weeks or longer showed weight benefits only against unrestricted eating [2]. An earlier Cochrane review found -0.88 kg against continuous energy restriction in the short term (very low certainty) and -0.56 kg (95% CI -1.68 to 0.56) at 3 to 12 months [5]. One 14-week trial found an early 7 a.m. to 3 p.m. window plus calorie restriction lost 2.3 kg more (95% CI -3.7 to -0.9) than calorie restriction over 12 hours or more, equal to eating 214 kcal a day less, and body fat did not differ [6].

Low-fat dietStrong

Weight loss against low-carbohydrate and other diets

Shown to produce about 1 to 2 kg less weight loss than low-carbohydrate diets in adults with overweight, and similar loss to other higher-fat diets of equal intensity.

Compared with low-carbohydrate diets, other higher-fat weight-loss diets and usual diet [3]; low-carbohydrate diets [4], [5]; no diet, and low-carbohydrate diets in the same network meta-analysis [6]; a healthy low-carbohydrate diet [7]

The numbers and sources

Effect: In weight-loss trials of a year or more, low-carbohydrate diets lowered weight 1.15 kg more than low-fat diets (95% CI 0.52 to 1.79, 18 comparisons, I² 10%). Low-fat diets did not differ from other higher-fat weight-loss diets (0.36 kg, 95% CI -0.66 to 1.37) and lost 5.41 kg more than usual diet [3]. In 11 RCTs lasting 6 months or more, weight fell 2.17 kg more on low-carbohydrate diets (95% CI 0.99 to 3.36) [4]. In 38 studies, the difference at 6 to 12 months was 1.30 kg (95% CI 0.57 to 2.02) [5]. Against no diet, low-fat diets lowered weight 7.99 kg at 6 months and 7.27 kg at 12 months, and low-carbohydrate diets 8.73 kg and 7.25 kg [6]. In a 12-month trial, weight fell 5.3 kg on a low-fat diet and 6.0 kg on a low-carbohydrate diet, a difference of 0.7 kg (95% CI -0.2 to 1.6) [7].
Population: 53 trials with 68,128 participants [3]; 1,369 previously healthy adults in 11 RCTs [4]; 6,499 adults in 38 studies [5]; 7,286 adults with overweight or obesity in 48 trials [6]; 609 adults aged 18 to 50 without diabetes, BMI 28 to 40 [7].
Sources: [3], [4], [5], [6], [7]
Caveats: Low-fat diets led to more loss only against usual diet, so the intensity of the comparison group drives the result [3]. The difference between diet types is small next to the loss on either diet [6]. In the 12-month trial, neither genotype pattern nor insulin secretion predicted who lost more on which diet [7].

5:2 dietModerate

Weight loss compared with daily calorie restriction

Not shown to cause more weight loss than daily calorie restriction in adults with overweight, obesity or type 2 diabetes over 6 to 12 months.

Compared with continuous energy restriction [1], [2], [3], [6]; continuous energy restriction and alternate-day fasting [4]; continuous calorie restriction [5]

The numbers and sources

Effect: In premenopausal women, weight changed by -6.4 kg (95% CI -7.9 to -4.8) on 5:2 and -5.6 kg (95% CI -6.9 to -4.4) on daily restriction over 6 months (P 0.4) [1]. In adults with abdominal obesity, weight loss at one year was 8.0 kg against 9.0 kg (p 0.6), and regain was 1.1 kg against 0.4 kg [2]. In type 2 diabetes, weight change at 12 months was -6.8 kg against -5.0 kg (P .25) [3]. A network meta-analysis found whole-day fasting did not lose more weight than continuous energy restriction, and alternate-day fasting lost 1.05 kg more than whole-day fasting [4]. Across 24 trials of intermittent fasting, weight loss matched continuous restriction (MD 0.26 kg, 95% CI -0.31 to 0.84) [5]. In adolescents with obesity, BMI z score fell 0.28 on both intermittent and continuous restriction at 52 weeks [6].
Population: 107 premenopausal women with overweight or obesity [1]; 112 adults aged 21 to 70 with BMI 30 to 45 [2]; 137 adults with type 2 diabetes [3]; 99 trials with 6,582 adults [4]; 24 trials with 1,768 people [5]; 141 adolescents aged 13 to 17 with obesity-related complications [6].
Sources: [1], [2], [3], [4], [5], [6]
Caveats: In the diabetes trial, the weight difference of -1.8 kg did not meet the prespecified equivalence margin (90% CI -3.7 to 0.07) [3]. The network meta-analysis abstract reports whole-day fasting as a group without separating 5:2 schedules [4], and [5] pooled 5:2 with alternate-day fasting and time-restricted eating.

Sirtfood dietUntested

Weight loss

Not studied in people. The diet rests on lab work suggesting some food compounds activate sirtuins, enzymes that carry some effects of calorie restriction.

No study in people. This rests on lab studies, how it acts in the body.

The numbers and sources

Effect: A 2022 review describes sirtuins as mediators of calorie restriction whose activation can produce some similar effects, and lists food compounds such as resveratrol, piceatannol and anthocyanidins as potential sirtuin modulators involved in energy balance and obesity [2]. In people, resveratrol did not change SIRT1 gene expression, protein expression or blood levels across 11 randomized trials [3].
Population: Studies of sirtuin biology and food compounds, reviewed [2]. Adults in 11 RCTs of resveratrol [3].
Sources: [2], [3]
Caveats: No trial of the Sirtfood diet or of sirtfood intake and weight was located. A pooled human test of the mechanism, for one sirtfood compound, found no change [3].

Devices and wearables

Wrist heart rate and calorie estimatesStrong

Body weight

Shown to lower body weight by about 1 kg across systematic reviews of activity tracker trials.

The numbers and sources

Effect: The same umbrella review found improvements in body composition (SMD 0.7 to 2.0), equal to reductions of about 1 kg in body weight [18].
Population: Participants in 39 systematic reviews and meta-analyses [18].
Sources: [18]
Caveats: The reviews cover wearable activity trackers as a class and do not isolate wrist heart rate or calorie readings [18].

Continuous glucose monitors in people without diabetesModerate

Body weight

Mixed results: pooled trials found no significant change in body mass index with sensor use, while single small trials ranged from no difference to 5 kg more weight loss.

The numbers and sources

Effect: In people without diabetes, body mass index did not differ between sensor users and controls (SMD -0.25, 95% CI -0.63 to 0.12, P = 0.19) [10]. Across trials mostly in diabetes, differences in weight (-0.7 kg, 95% CI -1.4 to 0.0) and body mass index (-0.4, 95% CI -0.9 to 0.0) were not statistically significant [14]. In 35 women with overweight or obesity in a 12-week exercise and diet program, those who also used a sensor at the midpoint lost 5.5 kg against 0.2 kg in controls (P < 0.001) [17]. In 39 overweight adults with impaired glucose tolerance or mild type 2 diabetes, 24-week weight change did not differ (-1.8 kg with a sensor, -2.2 kg without) [18].
Population: 1,074 participants without diabetes in 23 studies [10]. 2,996 participants in 25 trials [14]. 35 women [17]. 39 adults [18].
Sources: [10], [14], [17], [18]
Caveats: The authors of one review concluded a sensor is unlikely to achieve weight goals on its own without accompanying behavioral intervention [10]. The single trials were small and unblinded, and baseline body mass index differed between groups in one [18].

Lab markers

EstradiolLimitedStudied in men

Body fat and sexual function in a trial that lowered estradiol in men

One trial found that blocking estradiol production in men aged 20 to 50 increased body fat and contributed to lower sexual function, while lean mass and strength followed testosterone.

The numbers and sources

Effect: Men were given a drug that suppressed their own testosterone and estradiol, then placebo or one of four doses of testosterone gel for 16 weeks. A second group also took anastrozole, which blocks the conversion of testosterone to estradiol. The authors concluded that androgen deficiency accounted for the decreases in lean mass, muscle size and strength, that estrogen deficiency primarily accounted for the increases in body fat, and that both contributed to the decline in sexual function [12].
Population: 198 men aged 20 to 50 without anastrozole and 202 with it, treated for 16 weeks [12].
Sources: [12]
Caveats: One trial of 16 weeks in which hormone levels were set by drugs. The abstract gives no effect sizes for estradiol [12].

IGF-1Strong

Body composition and adverse events in trials of growth hormone

Shown in trials of growth hormone to shift fat and lean mass by about 2 kg in older adults, with more swelling, joint pain and carpal tunnel syndrome.

The numbers and sources

Effect: IGF-1 manages the effects of growth hormone in the body [1], and these trials gave growth hormone without aiming at an IGF-1 level. In community-dwelling adults with a mean age of 69 who were not being treated for a specific illness, growth hormone lowered fat mass by 2.1 kg (95% CI 1.35 to 2.8) and raised lean mass by 2.1 kg (1.3 to 2.9), with no change in weight, bone density or most blood lipids. Treated people were more likely to have soft tissue swelling, joint pain, carpal tunnel syndrome and breast growth in men, and somewhat more likely to develop diabetes or impaired fasting glucose [10]. In adults with confirmed growth hormone deficiency, it lowered weight by 2.31 kg (1.96 to 2.66) and body fat by 2.56 kg (2.16 to 2.97) and raised lean mass by 1.38 kg (1.10 to 1.65). Swelling had a relative risk of 6.07 (4.34 to 8.48) and joint stiffness 4.17 (1.4 to 12.38), with no significant change in bone density. Quality of life improved in 11 of 16 trials [11].
Population: 220 treated participants in 18 study populations, mean treatment 27 weeks [10]. More than 3,400 patients in 54 randomized trials [11].
Sources: [10], [11], [1]
Caveats: A marker that tracks an outcome is not always one whose correction changes it. Low IGF-1 went with more deaths in cohorts, and these trials measured body composition, not deaths. The trials in older adults were small and short [10].