1. Home>
2. Specialties>
3. General Medicine>
4. Summary and Comment

Four Low-Calorie Diets Yield the Same Mediocre Results

Dieters ate different amounts of protein, fat, and carbohydrate — but, after 2 years, most were still obese.

Most weight-loss diets claim unique nutrient compositions that guarantee unusually rapid and effortless success. Comparative studies — usually with small populations and short follow-ups — have yielded widely disparate results. Now, a large long-term multisite study suggests that all these diets result in similar outcomes.

Researchers randomized 811 overweight adults (81% white; 62% female; 69% college graduates; mean body-mass index, 33 kg/m²) to four restricted-calorie eating plans:

• High fat, high protein
  
• High fat, average protein
  
• Low fat, high protein
  
• Low fat, average protein
  

Carbohydrate intake ranged from 35% (in the first plan) to 65% (in the fourth) of total calories. All meals were prepared at home, and participants ate from a single menu with each dish’s components adjusted to reflect each diet’s emphasis; all participants were offered weight-loss counseling.

Changes in weight and waist circumference at 6, 12, 18, and 24 months were indistinguishable among groups: At 2 years, only about 15% of each group had lost at least 10% of body weight. Attendance at group counseling sessions strongly predicted successful weight loss. At 2 years, hunger and diet-satisfaction scores were all similar. Food diaries and urinary nitrogen analyses indicated that the actual nutrients consumed might have been more similar among groups than had been planned.

Comment: The most Draconian low-carb and low-fat regimens were excluded from this study, but other popular diet plans led to identical weight-loss patterns. Perhaps the average dieter’s enthusiasm for counting out 14 walnut halves for a high-fat dinner simply wanes, rendering the nutrient composition of all limited-calorie eating plans pretty much the same. The authors conclude that the behavioral trappings of dieting — such as group counseling — rather than the nutrient composition lead to weight-loss success. A pessimistic editorialist likens obesity in adults to cholera as an epidemic that cannot be "cured" without community action and suggests that prevention during childhood is the key to combating obesity.

— Abigail Zuger, MD

Published in Journal Watch General Medicine February 25, 2009

Citation(s):

Sacks FM et al. Comparison of weight-loss diets with different compositions of fat, protein, and carbohydrates. N Engl J Med 2009 Feb 26; 360:859.

• Original article (Subscription may be required)
• Medline abstract (Free)

Katan MB. Weight-loss diets for the prevention and treatment of obesity. N Engl J Med 2009 Feb 26; 360:923.

• Original article (Subscription may be required)
• Medline abstract (Free)