Cardiologist Dr. Agatson’s South Beach Diet book is a New York Times Best Seller, both because of its nutritional advice and the popularity of the low carb diets which were made popular by earlier work by another cardiologist, Dr. Atkins. Dr. Agatson’s advice is similar to that of the “traditional low carb” diet but at the same time, it is a little different. At the outset, the book distinctly states that “South Beach Diet is not low carb, nor is it low fat.” The difference is that SBD spends a lot of time discussing about the right kinds of carbs – and the right kinds of fats. In this article, we review the book itself, as well as refer you to some additional background research for consideration of the South Beach Diet.
South Beach Diet, the Book
Similar to other low carbohydrate diets, Dr. Agatson’s South Beach Diet recommends that you limit the consumption of carbs. However, unlike other low-carb diets there is no absolute restriction on the total amount of carbs. As the reader should avoids certain foods, the consumed carbs are reduced. Also like the other low carb diets, the South Beach Diet encourages the reader to eat until you are full. But, unlike other low carb diets, the fats Dr. Agatson is encouraging the reader to eat are unsaturated fats. The South Beach Diet’s advice is to use the “good” fats like olive or canola oils, low-fat cheeses or milk. The low saturated fat advice seems to be echoed by published research that we came across performing background research for this article. In a 1991 study titled “Low Carbohydrate Diet Score and the risk of Coronary Heart Disease in women,” published in the New England Journal of Medicine, Thomas Halton et al. echo Dr. Agatson’s advice with the conclusion that “diets lower in carbohydrate and higher in protein and fat were not associated with an increased risk of coronary heart disease… When vegetable sources of fat and protein were chosen, these diets were related to a lower risk of coronary heart disease.”
In general, like the Atkins Diet, the South Beach Diet book recommends to approach the diet in three phases (initial two week phase, subsequent measured additions of carbs that get to a full range of foods, and the third “lifetime” maintenance phase). Since people’s health conditions are frequently a product of poor choices over a long period of time, the South Beach Diet should be viewed more like a change in lifestyle habits rather than something that one does for a little bit. Dr. Agatson also writes briefly on the subject of exercise, but the main thrust of the book is aimed at the diet itself. For more information on exercise and its role in successfully losing weight, please visit our 20BMI.com Exercise Archive. The book is clearly written and well edited, so reading it gets the reader at the information Dr. Agatson wanted to convey with minimal digressions along the way. In fact, the book is relatively compact – about 100 pages are “the book,” the rest being meal plans and recipes. There are also lots of stories of people applying the South Beach Diet and succeeding, as well as some stories of people failing. The author dedicates an entire chapter to why people fail on this diet. Like the rest of the book, this chapter is more of a survey and discussion of reasons, rather than an exhaustive, in-depth list and discussion of all of the reasons in depth. There are some additional resources available for successfully following the South Beach Diet, please see below.
Research that Supports the South Beach Diet
Of the published research that we came across, we find it to be generally supportive of the South Beach Diet (and the low-carb diet concepts in general). Please note, there seems to be more references in scientific literature to the “Atkins Diet” or to the “low carb diet” rather than to the “South Beach Diet.” We believe that the Atkins Diet comparison is appropriate as the both it and the South Beach diets are similar in the key principle of reduction of consumed carbs. As always, you should check with your physician before starting on any diet or exercise program.
One of the biggest challenges that people experience when they are dieting is dealing with the whatever limitations are imposed upon them by the particular diet over the long term. In fact, after the initial resolve to lose weight wears off, people start to cheat here and there – either because of pressure of work and home, or for self-indulgent reasons. In a supportive environment, the rates of “diet drop-outs” reported in research that we have reviewed appeared to be fairly low. People engaged in the studies seem to be sticking to the protocol well, even over a relatively long term period (one of the studies we examined, the Shai study, stretched over two years). In a study by Christopher D. Gardner et al. titled “Comparison of the Atkins, Zone, Ornish and LEARN Diets…,” published in Journal of the American Medical Association, of the 77 people assigned to the Atkins Diet group, 68 completed the study after one year (9 people, or 12% withdrew). Similarly, the Shai study (referenced below) noted that 90% of the people assigned to its low-carb group completed the two year study. The Shai study went through all three phases of a low carb diet during its two year run.
South Beach Diet and Weight Loss
A 2008 study titled “Weight Loss with a Low Carbohydrate, Mediterranean or Low Fat Diet,” published in the New England Journal of Medicine (Iris Shai, Dan Schwarzfuchs et al.) found that subjects following the low carb diet lost the most weight at the end of the study period. In fact, the Shai study concludes that a low carbohydrate diet is an “effective alternative to the low fat diet and appear[s] to be just as safe.” In this study, subjects lost 5.5 kg (over 14 pounds, on average at the end of two years).
An earlier study of studies conducted by Alain Nordmann et al., titled “Effects of Low Carbohydrate vs. Low-Fat Diets on Weight Loss and Cardiovascular Risk Factors,” and published in the Archives of Internal Medicine combined results of six different scientific articles (447 subjects, of which 222 were on the low-carb diet and 225 were on the low-fat diet). In all but one of the sub-studies, the low carb subjects lost more weight on average (6 and 12 month follow ups) than the low-fat subjects. Their similar conclusion was that “the low-carbohydrate diets appear to be at least as effective as low-fat diets in inducing weight loss for a duration of up to 1 year.” (The study-of-studies format is where the researchers comb through the findings of other research and aggregate it, hoping to find supportive trends).
In all, of the research that we have surveyed, we found a consensus that South Beach (or similar low-carb diets) is effective for weight loss, but that more long-term study needs to be done to assess their effects on blood chemistry (lipids, cholesterol, insulin, etc.). Such studies appear to be in the works, as not less a body than the National Institute for Health is now sponsoring a five-year study. This is significant because the NIH, along with the American Medical Association opposed the low carb diets for a 20 – 30 years, and their research investment should be probably be viewed as a curious interest in a question that their opposition may have been wrong. The NIH Study was financed in 2005, and is expected to compare the low carb and low fat diets over five years. (NIH Clinical Trials Reference Number: NCT00143936). At present, there is little long-term research on this subject (long term being defined as over one year).
South Beach Diet and Cholesterol
Generally, our survey of scientific research points to a positive cholesterol reaction to a low carbohydrate diet. Remember that you consume is only a portion of your total cholesterol (your body actually manufactures a good portion of your total cholesterol). This is why physicians will prescribe drugs to control cholesterol if dietary changes alone are not effective. This is also why it is important that you consult with your physician before embarking on any diet or exercise program, South Beach or other. The Shai study (referenced above) found that following the low-carb diet for two years elevated the “good” HDL cholesterol by 8.4 mg/dl, while it lowered the “bad” LDL cholesterol by 3 mg/dl. The ratio of the HDL:LDL Cholesterol dropped by 1.1 mg/dl (the most of any of the diets compared, including the low-fat diet). The Shai study concluded that the low-carb diet had “favorable effects on lipids.”
The older Nordmann et al. study had mixed results, reporting increased levels of both “good” and “bad” cholesterols, as did the Gardner et al.study. In some studies, the HDL cholesterol increased more than the LDL cholesterol, favorably increasing the cholesterol ratio. (It should be noted that there is some debate among medical professionals whether the cholesterol ratio or absolute cholesterol should be the “real” metric).
Similarly, a 2003 study published in the New England Journal of Medicine, by Foster et al., found that people in the low carb diet group had significantly improved HDL cholesterol and triglycerides as compared to the low-fat diet group, but that LDL and total cholesterol measurements were better for the group following the low-fat diet.
Conclusions
The South Beach Diet book is clearly written and effectively conveys its information to the person that is interested in learning about this diet. The meal plans presented allow a broad array of options. While the book itself is not overly detailed on exploring the research behind the benefits of a low carbohydrate diet, there do seem to be scientific conclusions that the low carb diets may be effective to to help the reader lose weight, relatively quickly. 
Furthermore, the South Beach Diet book does make strong strides to present a plan that is easy to follow. There are many recipes (in fact, 2/3 of the book) to keep the reader from feeling restricted by in the program. For those that would prefer even more options, the diet’s official website has over a thousand of recipes available, and there are published South Beach Diet recipe books. Signing up at the book’s website provides other program support such as additional information on the diet, its author, weight loss information and assistance with meal plans, tools and support. Members can also get their questions answered by Dr. Agatson.
Additional Resources
Learn more about the South Beach Diet website here.
Low Carb Diet Category on 20bmi.com
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