South Beach diet
No large trials of the South Beach diet were located. In a 12-week uncontrolled study of 20 adults with metabolic syndrome, weight fell 5.2 kg and fasting insulin fell, while hunger and ghrelin rose. A small trial after gastric bypass found no weight difference from a low-fat diet. One case report describes ketoacidosis after 3 weeks on the diet.
- Status
- A commercial diet program, not a regulated product.
- Also called
- South Beach, South Beach Diet
- Followed for
- weight loss, blood sugar, insulin resistance, heart health
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
Shown to help2
- LimitedLimited evidence: weight fell 5.2 kg over 12 weeks in one uncontrolled study, and a small trial after gastric bypass found no difference from a low-fat diet.
- LimitedLimited evidence: fasting insulin fell from 139 to 99 pmol/L over the first 2 weeks in 20 adults with metabolic syndrome, with no control group.
Reported risks3
- LimitedLimited evidence: fasting ghrelin and self-reported hunger rose over 12 weeks in 20 adults with metabolic syndrome.
- LimitedCase reports: a 30-year-old man had ketoacidosis with vomiting and abdominal pain after 3 weeks on the diet and a 16-pound weight loss.
- LimitedLimited evidence: internet recipe searches suggest January starters kept to South Beach about 3 weeks, the shortest of the popular diets compared.
What people follow it for, and what was found
Shown to help2
Weight loss
Limited evidence: weight fell 5.2 kg over 12 weeks in one uncontrolled study, and a small trial after gastric bypass found no difference from a low-fat diet.
Compared with a low-fat control diet based on American Heart Association recommendations, after gastric bypass [1]; before the diet, in the same people [2]
The numbers and sources
- Effect
- After gastric bypass, BMI fell 17.0% on a diet based on South Beach and 14.0% on a low-fat diet at 12 months (p 0.15), and excess weight lost was 59.6% against 60.3% (p 0.96) [1]. In adults with metabolic syndrome, weight fell from 93.5 to 88.3 kg, waist from 112.8 to 107.7 cm and body fat from 40.2% to 39.2% over 12 weeks [2].
- Population
- 32 patients after laparoscopic gastric bypass, 19 on the South Beach based diet and 13 on low-fat [1]; 20 adults with overweight or obesity and metabolic syndrome, 16 women, no control group [2].
- Sources
- [1], [2]
- Caveats
- Two small studies, one without a comparison group [2]. Both groups lost similar weight after surgery [1].
Blood sugar and insulin
Limited evidence: fasting insulin fell from 139 to 99 pmol/L over the first 2 weeks in 20 adults with metabolic syndrome, with no control group.
Compared with before the diet, in the same people [2]
The numbers and sources
- Effect
- Fasting insulin fell from 139.1 to 98.6 pmol/L and leptin from 44.1 to 33.3 μg/L by the end of the 2-week first phase [2].
- Population
- 20 adults with overweight or obesity and metabolic syndrome [2].
- Sources
- [2]
- Caveats
- One small study with no control group, so the change cannot be separated from weight loss in general [2].
Not yet researched1
Heart health
We haven't sourced research on this yet.
How trials defined it
In one study, people received clinical instruction in the commercial diet's two phases, the first for 2 weeks and the second for the remaining 10 weeks [2]. In a trial after gastric bypass, a low-carbohydrate, high-protein diet based on South Beach was taught through one-on-one counseling with a bariatric nutritionist over 12 months [1].
Risks
Reported risks3
Hunger
Limited evidence: fasting ghrelin and self-reported hunger rose over 12 weeks in 20 adults with metabolic syndrome.
The numbers and sources
Ketoacidosis
Case reports: a 30-year-old man had ketoacidosis with vomiting and abdominal pain after 3 weeks on the diet and a 16-pound weight loss.
The numbers and sources
- Effect
- A 30-year-old man presented with nausea, vomiting and abdominal pain, bicarbonate of 12, high blood sugar and ketones. He was treated for diabetic ketoacidosis, kept normal blood sugar without insulin afterward, and had no symptoms over 2 years after stopping the diet [3].
- Population
- One case report [3].
- Sources
- [3]
- Caveats
- A single case. The authors advise ruling out other causes before attributing acidosis to a low-carbohydrate diet [3].
Staying on the diet
Limited evidence: internet recipe searches suggest January starters kept to South Beach about 3 weeks, the shortest of the popular diets compared.
The numbers and sources
- Effect
- Modeling of US recipe searches from 2004 to 2019 estimated that new January dieters kept to South Beach for 3.12 weeks on average, the shortest of the diets compared, and 33% dropped out in December, the highest share [4].
- Population
- US internet searches, not individual people [4].
- Sources
- [4]
- Caveats
- Search behavior is an indirect measure of adherence [4].
Sources
- Swenson BR, Saalwachter Schulman A, Edwards MJ, et al. The effect of a low-carbohydrate, high-protein diet on post laparoscopic gastric bypass weight loss: a prospective randomized trial. Journal of Surgical Research. 2007. https://doi.org/10.1016/j.jss.2007.02.052
- Hayes MR, Miller CK, Ulbrecht JS, et al. A carbohydrate-restricted diet alters gut peptides and adiposity signals in men and women with metabolic syndrome. The Journal of Nutrition. 2007. https://doi.org/10.1093/jn/137.8.1944
- Chalasani S, Fischer J. South Beach Diet associated ketoacidosis: a case report. Journal of Medical Case Reports. 2008. https://doi.org/10.1186/1752-1947-2-45
- Towers S, Cole S, Iboi E, et al. How long do people stick to a diet resolution? A digital epidemiological estimation of weight loss diet persistence. Public Health Nutrition. 2020. https://doi.org/10.1017/s1368980020001597