The Physician and Sportsmedicine
Menubar Home Journal Personal Health Resource Center CME Advertiser Services About Us

News Briefs


The South Beach Diet

Weighing the Pros and Cons

When patients say they're "beaching" their New Year's resolution to lose weight, it might not mean they're giving up. Instead, it's likely to mean that they're flocking to the hottest new weight loss plan, the South Beach diet.

Detailed in a book that has been on the New York Times best-seller list for more than 35 weeks, the South Beach diet, developed by Miami cardiologist Arthur Agatston, MD, is billed as neither a low-carbohydrate diet nor a low-fat diet.1 Agatston's goal is to teach dieters to select the right carbohydrates and the right fats. The three-part diet consists of the following steps:

  • Phase 1. Designed to reduce dieters' cravings for carbohydrates, the plan starts with 2 weeks of avoiding bread, rice, potatoes, pasta, baked goods, sweets, alcohol, and fruit. Dieters are encouraged to eat normal-size portions of meat, poultry, fish, and seafood, accompanied by vegetables, eggs, cheese, and nuts. Dieters are told to expect to lose between 8 and 13 lb during phase 1.
  • Phase 2. Carbohydrates are gradually reintroduced in limited amounts. The plan encourages the selection of low-glycemic-index food choices. Dieters remain in phase 2 until they reach their weight goal.
  • Phase 3. Carbohydrate intake is liberalized to a level that allows dieters to maintain their ideal weight. Normal-sized portions of all foods are encouraged, and dieters are urged to continue to adhere to the basic rules of the South Beach diet.

Glycemic Index Trends

The South Beach diet is one of several popular diet plans that are based on the glycemic index. The glycemic index is a ranking (0 to 100) of how different foods, when eaten alone, influenced insulin levels in a group of test subjects.

Researchers had hoped that the index would serve as a tool to assist patients who have diabetes monitor their dietary intake; however, the American Diabetes Association has never officially incorporated the glycemic index into its dietary recommendations.

The American Institute for Cancer Research (AICR), which recently outlined several questions about the glycemic index, says that it is concerned that diets that favor a low-glycemic-index approach encourage patients to favor satiating foods that are high in fat and protein over pasta, bread, and vegetables. Diets rich in high-fat foods and meat have been linked to increased risk of colorectal cancers, according to the AICR.

The group also notes that the glycemic index of a food varies from person to person, and that several research questions need to be resolved, such as calculation method and the applicability of the index to meals rather than single foods eaten alone.

Experts Weigh In

Marna Canterbury, MS, RD, LD, population health and nutrition specialist for HealthPartners, a Minneapolis-based healthcare organization, has evaluated the South Beach diet and heard from patients who have used the diet. Canterbury gives the South Beach diet a mixed review. "There are worse diets out there, but there are also much better diets," she says.

The main safety concern for some patients, she says, is the initial 2-week phase that induces ketosis. Risks associated with ketosis include loss of glycogen stores, dehydration, dizziness, heart palpitations, fatigue, lightheadedness, constipation, irritability, and electrolyte imbalance. "Ketosis suppresses appetite, and people often think they're feeling fine until they try to exercise," she notes. She advises that certain patients consult with their physicians before starting the South Beach diet, especially those with chronic illness, a history of heart disease, diabetes, or kidney disease, and those who are significantly overweight.

In the phase 2 part of the South Beach diet, protein choices seem to be lower in fat than some of the popular low-carbohydrate diets, Canterbury says. She also lauds the inclusion of low-fat dairy products and whole-grain foods such as steel-cut oats. Her main concern about phase 2 is that its foundation rests on a list of 90 foods, which she views as an overly restrictive way to eat. The list excludes many nutritious and convenient foods such as carrots, canned fruit, and bananas.

Canterbury says patients generally lose weight on diets that have food lists because such diets tend to be lower in calories; however, some patients may not stick to such diets because they find that the food choices are too limited.

Donald M. Christie, Jr, MD, an internist and sports physician in Lewiston, Maine, calls the South Beach diet "Atkins lite." "It seems to appeal to Atkins dropouts who tired of the severe carbohydrate restriction," he says. Christie says phase 2 and 3 of the South Beach diet are more nutritionally balanced—incorporating more vegetables, fruit, and whole-grain foods—than the Atkins plan, which advises dieters to employ multivitamin, mineral, and fiber supplementation. "The South Beach diet also follows the accepted strategy of frequent small feedings," he says.

The major deficiency of the South Beach diet, Christie says, is the absence of any significant mention of exercise. "Likewise, Atkins gave only lip service to exercise," he says, adding that both diets seem to favor the quick appeal of ketogenic weight loss over a properly designed exercise prescription.

The Bottom Line

Earl Carstensen, MD, a family physician in Aurora, Colorado, says that the South Beach diet appears to be safe and effective for weight loss but, like other popular diets, is an effective tool only when patients stick to the diet plan. "If your goal is long-term health and appropriate body composition, the answer is simple, but not easy: Eat a sensible array of various foods and walk briskly for 30 minutes a day," he says. "But that doesn't sell books." Carstensen advises patients to follow a simple rule: If it's packaged or processed, eat very little of it.

Canterbury advises patients to look beyond diet trends toward more important lifetime dietary goals. Even with leaner cuts of meat promoted in some of the newer diets, saturated fat content can quickly surpass the American Heart Association's approximately 20 g/day recommendation. "I tell them to do everything they can to have the best overall health today and in the future, not just weight loss," she says.

Lisa Schnirring


  1. Agatston A: The South Beach Diet. Emmaus, PA, Rodale Press, 2021

Field Notes

Fitness Trends for 2021

The American Council on Exercise, a group that certifies fitness professionals and researches, monitors, and reports on fitness products and trends, recently made its predictions on the latest exercise trends for 2021. The top 10 developments to watch for are:

  • Fitness programs that offer quicker, more efficient workouts,
  • Traditional fitness programs that incorporate elements of mind-body activities such as yoga and Pilates,
  • A functional strength training approach that works groups of muscles and joints, rather than isolated muscles, to ease daily activities and improve athletic performance,
  • Lifestyle and performance coaching by phone and internet that addresses not only fitness but also stress reduction, time management, and wellness issues,
  • Healthcare providers and companies that offer, and partially subsidize, preventive lifestyle programs that will also include online health and fitness resources for employees,
  • "Smarter," more efficient, and more portable fitness equipment,
  • Alternative, more flexible, pricing by health clubs,
  • A back-to-basics approach to diet and exercise that focuses less on trends and more on regular exercise and sensible diet,
  • Exercise programs, focusing on balance, stability, and strength training, as preventive care for seniors, and
  • Activity interventions focused on sedentary individuals—for example, instituting walking programs and building sidewalks and trails.