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The South Beach diet is a lower-carbohydrate eating plan created by Miami cardiologist Arthur Agatston and popularized by his 2003 book. It runs in three phases: a strict two-week start that cuts most starches, sugars and fruit, a second phase that adds whole grains and fruit back, and a maintenance phase. Unlike stricter low-carb plans, it stresses the type of carbohydrate and fat rather than cutting carbohydrate as far as possible. The research behind it is limited: one small 2004 trial co-authored by Agatston and a few trials pooled in a 2020 BMJ review, rated as low or very low certainty evidence.
Peptide Labs does not sell South Beach Diet products or meal plans. This article is general nutrition information, not medical advice.
Key Takeaways
- The South Beach diet was developed by cardiologist Arthur Agatston and published as a book in 2003.
- It has three phases: a two-week restrictive start, gradual reintroduction and lifelong maintenance.
- It favors lean protein, vegetables, unsaturated fats and higher-fiber carbohydrates over refined ones.
- A 2020 BMJ network meta-analysis classed it as a low-carbohydrate diet with low-certainty evidence.
- As with other named diets, average weight differences tended to shrink by 12 months.
Where the South Beach diet came from
Agatston, a cardiologist in Miami, developed the plan to help his heart patients lose weight and improve cholesterol, according to WebMD’s review of the program. His book The South Beach Diet came out in 2003 and became a bestseller. The core message was that you do not have to cut all carbohydrates or all fats, only swap refined carbohydrates for higher-fiber ones and saturated fats for unsaturated ones, an idea summed up as eating the right carbs and the right fats.
The brand changed hands over the years. The weight-loss company Nutrisystem bought South Beach Diet in December 2015 and relaunched it with packaged foods and delivery plans. At the end of 2019, Agatston published The New Keto-Friendly South Beach Diet, a version with fewer carbohydrates and more fat. So the name now covers both the original book and a commercial program; the evidence below concerns the original eating pattern.
South Beach diet phases at a glance
The South Beach diet phases are summarized below as a description of how the book structures the plan, not as instructions to follow. Anyone considering a restrictive start should check with a clinician first, particularly if they take medicines.
| Phase | Length | Broad food pattern | Stated aim |
|---|---|---|---|
| Phase 1 | Two weeks | Lean protein, non-starchy vegetables, unsaturated fats; most starches, fruit, fruit juice and alcohol cut | A quick start and fewer cravings |
| Phase 2 | Until a goal is reached | Gradual return of fruit, whole-grain bread, brown rice, whole wheat pasta and sweet potatoes | Slower, steadier progress |
| Phase 3 | Ongoing | No fixed food list; lean protein, healthy fats and higher-fiber carbohydrates | Long-term maintenance |
South Beach diet phase 1 is the part most people have heard of, because it is the strictest. It is meant to last two weeks. Short-term weight changes on any plan that suddenly cuts carbohydrate include shifts in water as well as fat, a point our guide to the weight loss plateau explains, so early scale numbers can overstate progress.
South Beach diet foods: what the swaps look like in USDA data
The plan’s central move is swapping refined starches for higher-fiber carbohydrates and building meals around protein and vegetables. The table compares typical servings from USDA FoodData Central SR Legacy data. It illustrates the swaps; it is not a meal plan or a set of portions to eat.
| Food (USDA FDC ID) | Serving | Calories | Carbohydrate | Fiber | Protein |
|---|---|---|---|---|---|
| White bread (174924) | 1 slice (29 g) | 77 | 14.3 g | 0.8 g | 2.6 g |
| Whole-wheat bread (172688) | 1 slice (32 g) | 81 | 13.7 g | 1.9 g | 4.0 g |
| White rice, cooked (168878) | 1 cup (158 g) | 205 | 44.5 g | 0.6 g | 4.3 g |
| Brown rice, cooked (169704) | 1 cup (202 g) | 248 | 51.7 g | 3.2 g | 5.5 g |
| Potato, baked (170093) | 1 medium (173 g) | 161 | 36.6 g | 3.8 g | 4.3 g |
| Sweet potato, baked (168483) | 1 cup (200 g) | 180 | 41.4 g | 6.6 g | 4.0 g |
| Lentils, cooked (172421) | 1 cup (198 g) | 230 | 39.9 g | 15.6 g | 17.9 g |
| Strawberries (167762) | 1 cup halves (152 g) | 49 | 11.7 g | 3.0 g | 1.0 g |
| Broccoli, raw (170379) | 1 cup chopped (91 g) | 31 | 6.0 g | 2.4 g | 2.6 g |
| Chicken breast, roasted (171477) | 3 oz (85 g) | 140 | 0 g | 0 g | 26.4 g |
| Almonds (170567) | 1 oz (28 g) | 164 | 6.1 g | 3.5 g | 6.0 g |
The numbers show what the swaps do and do not change. Whole-wheat bread and brown rice carry more fiber and protein than their white versions, but similar or slightly higher carbohydrate and calories. Lentils bring far more fiber and protein per cup. Non-starchy vegetables and berries add volume for few calories. For longer lists, see our guides to fiber-rich foods, lower-carb foods and protein foods.
The plan also leans on the idea of how quickly a carbohydrate raises blood sugar, a measure introduced by David Jenkins and colleagues at the University of Toronto in 1981, who fed 62 foods to healthy volunteers and compared their blood glucose responses with pure glucose. Fiber, fat and protein in a meal slow that rise, which is part of the reasoning behind pairing carbohydrates with protein and vegetables. Our guides to low-glycemic eating and sugar cravings cover related research.
What the evidence shows
Direct research on the South Beach diet is sparse. The main trial is small and was run by the diet’s creator; the larger picture comes from reviews that pool it with similar diets.
- 2004 randomized trial (Aude, Agatston and colleagues, Archives of Internal Medicine): 60 adults followed either a standard National Cholesterol Education Program diet or a modified lower-carbohydrate diet higher in protein, monounsaturated fat and complex carbohydrates, with similar calories, for 12 weeks. The lower-carbohydrate group lost more weight on average (13.6 versus 7.5 pounds). Cholesterol and triglyceride changes did not differ significantly between groups. The trial was short, small and co-authored by Agatston.
- 2020 network meta-analysis (Ge and colleagues, BMJ): 121 trials with 21,942 adults with overweight or obesity comparing 14 named diets. The authors grouped South Beach with Atkins and Zone as low-carbohydrate diets. At six months, low-carbohydrate and low-fat patterns produced similar average weight loss compared with usual diets, and low-carbohydrate patterns lowered LDL cholesterol less. Among diets backed only by low or very low certainty evidence, South Beach looked possibly the most effective. Across nearly all diets, average weight differences shrank by 12 months.
The fair summary is that the South Beach diet performs roughly like other structured lower-carbohydrate approaches in short trials, the evidence is weak, and no named diet has shown a lasting advantage on average. The plan people can keep following tends to matter more than its label. Our guide to hunger hormones explains why appetite often pushes back over time.
South Beach diet vs keto and other lower-carb approaches
The main differences come down to how far carbohydrate is cut and how much attention goes to the type of fat:
- South Beach diet vs keto: a ketogenic diet restricts carbohydrate far enough for the body to make ketones and keeps it low long-term. The original South Beach plan is strict only in its first two weeks and then adds whole grains and fruit back. Our guide to ketone supplements explains ketosis.
- South Beach vs Atkins and Zone: the 2020 BMJ review placed all three in its low-carbohydrate group, at or under about 40% of calories from carbohydrate. South Beach puts more explicit weight on choosing unsaturated fats and higher-fiber carbohydrates.
- South Beach vs eating patterns with more carbohydrate: moderate-carbohydrate patterns in the same review produced slightly less weight loss at six months but often larger LDL cholesterol improvements, so the right fit depends on a person’s health goals and lab results.
For people taking GLP-1 medicines, the focus is usually on protein and fiber while appetite is low; our GLP-1 diet guide covers that. Our sibling guide to the alkaline diet looks at a diet whose theory falls apart even though its food list is reasonable.
Who should talk to a clinician first
Anyone taking medicines for diabetes or blood pressure should talk with their clinician before a sharp cut in carbohydrate, because medicines may need adjusting. The same goes for people who are pregnant or breastfeeding, have kidney disease, or have a history of disordered eating, for whom a restrictive start can be a poor fit. A registered dietitian can help turn the general principles into something realistic.
Frequently Asked Questions
What is the South Beach diet?
A lower-carbohydrate eating plan created by cardiologist Arthur Agatston and published in 2003. It emphasizes lean protein, vegetables, unsaturated fats and higher-fiber carbohydrates.
What are the South Beach diet phases?
Phase 1 is a strict two-week start, Phase 2 gradually adds fruit and whole grains back, and Phase 3 is ongoing maintenance without a fixed food list.
What happens in South Beach diet phase 1?
Most starches, fruit, fruit juice and alcohol are cut for two weeks while meals center on lean protein, vegetables and unsaturated fats.
Is the South Beach diet the same as keto?
No. Keto keeps carbohydrate very low long-term. The original South Beach plan is strict only at first, although a keto-friendly version was published in 2019.
Does the South Beach diet work?
Short trials show weight loss similar to other lower-carbohydrate diets, but the evidence is rated low certainty and differences between diets fade by 12 months.
Is the South Beach diet safe?
Its later phases resemble balanced eating patterns. People on diabetes or blood pressure medicines should check with a clinician before starting the restrictive first phase.
Questions about a label? Contact us or read our Buyer’s Guide. Food comes first; ask a healthcare provider before a major diet change or a new supplement, especially if you take medicines, are pregnant or have a chronic health condition. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
Last reviewed October 2026.
Related guides: Low Glycemic Foods: Glycemic Index Chart and Glycemic Load Explained, Low Carb Foods List: Vegetables, Fruits, Proteins and Nuts, Mediterranean Diet: What It Is, Food List and What the Research Shows.