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Nutrition & Weight Control From the Current Issue

Weighing in on the South Beach Diet
Should you try the diet of the moment? Here’s what you need to know.

You don’t have to live in the tony Miami neighborhood of South Beach to have heard about—and possibly even tried—The South Beach Diet. At press time, it had been on the New York Times list of hardcover advice books for over a year and was among the top 10 books sold at But will this diet plan work for you?

The Plan

In a nutshell, the South Beach Diet is a reduced-carbohydrate meal plan that is set up in three phases. Phase one, the most restrictive part of the plan, lasts two weeks and is designed to initiate rapid weight loss by eliminating most carbohydrates. Dieters are advised to go back on phase one of the plan if they experience any setbacks to weight loss, such as overindulging on vacation. Phase two allows dieters to resume eating more carbohydrates, including whole-grain breads and cereals, sweet potatoes, and most fruits, but limits the portion sizes of these foods. Phase three is the maintenance part of the meal plan and is supposed to be more flexible than the other two phases.

The premise behind the book is that overindulging in highly processed carbohydrates raises blood glucose levels, leading to surges in insulin that cause sugar cravings and weight gain. By limiting such carbohydrates, the South Beach Diet suggests that you can virtually eliminate cravings for carbohydrates and sugary sweets and lose weight—all without counting calories or measuring portion sizes.

Moreover, The South Beach Diet author, Dr. Agatston, claims that avoiding so-called “bad” carbohydrates such as white bread and sweets in favor of “good” ones like whole grains, fruits, and vegetables will cure insulin resistance and decrease your risk of coronary heart disease.

A Day in South Beach

Despite Dr. Agatston’s claims that the South Beach Diet “is distinguished by the absence of calorie counts; percentage counts of fats, carbs, and proteins; or even rules about portion size,” the meal plans involve recipes that state portion sizes, and portions are given for most items on the menus. Therefore, the diet ultimately restricts calories. In fact, a calorie analysis of day one on phases one and two reveals that a dieter who strictly follows the meal plan would consume about 1,500 calories a day; day one on phase three—the maintenance part of the plan—contains about 2,000 calories. Certainly, many people could lose weight on 1,500 calories a day and maintain their weight consuming 2,000 calories daily.

Weight and Insulin Resistance

The South Beach Diet suggests that overeating highly processed carbohydrates contributes to weight gain, which leads to insulin resistance. Though it’s true that overeating causes weight gain, the source of the calories doesn’t affect weight. In addition, the book oversimplifies the cause of insulin resistance. Although obesity is the more common cause of insulin resistance, genetic factors, diet, physical inactivity, cigarette smoking, and older age contribute to it as well.

The Glycemic Index

The meal plan in the South Beach Diet is built upon the glycemic index, which assigns each food a number based on the rise in blood glucose it produces during the first two hours after eating it compared with the rise triggered by eating an equivalent amount of carbohydrate in a standard food like white bread.

The South Beach Diet, particularly in phase one, calls for choosing foods that are low on the glycemic index in order to avoid surges in blood glucose. Moreover, the book suggests that consuming low-glycemic foods will curb your appetite and minimize your cravings. Again, this message is oversimplified.

According to the American Diabetes Association, the amount of carbohydrate consumed each day is more important in determining the body’s glucose response than the glycemic index of each individual carbohydrate.

Another problem with the index is that it is not practical. The index rates only single foods eaten individually, which is not the way people eat. Finally, the effect of a food on blood glucose levels can vary depending on whether a particular food is cooked or eaten in combination with other foods, and what the blood glucose level is before eating.

Furthermore, many nutritious foods, such as corn, carrots, and raisins, are high on the glycemic index, but that doesn’t mean they need to be eliminated in order to stay healthy or lose weight.

The Bottom Line

Despite some of the problems mentioned above, the South Beach Diet does make some good points, particularly about choosing whole-grain foods, fruits, and vegetables over processed carbohydrates. As Agatston points out, these foods contain fiber, which helps fill you up, but are naturally low in fat and calories. Furthermore, unlike Atkins—who revolutionized low-carbohydrate eating—Agatston focuses on lean meats, low-fat dairy products, and healthy sources of fats, like nuts and fish.

Though phase one severely limits carbohydrates, several clinical trials over the last few years have shown that dieters lose weight on these types of meal plans—at least in the short term. It’s possible that the initial weight loss will motivate people to remain on the diet. Phase two calls for filling up on lots of fruits and vegetables, along with lean meats and reduced fat cheeses, which is a reasonable way to lose weight. Finally, phase three allows for more carbohydrates from fruits and whole grains, which is a sensible plan for maintenance. Though South Beach does allow low-fat dairy products, most adults could benefit from additional servings to meet their calcium needs.

Of course, in addition to reducing calories, exercise is a critical component of a weight loss program. Though Dr. Agatston claims the South Beach Diet doesn’t depend on exercise in order to work, studies have shown that people who exercise are more likely to maintain their weight loss.


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