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Low-carbohydrate and Mediterranean diets are effective alternatives to traditional low-fat diets.
Although many weight-loss diets are touted as "the best" by their advocates, few high-quality comparative studies have been conducted. In this randomized trial, Israeli researchers compared three diets — a low-fat calorie-restricted diet based on American Heart Association guidelines, a moderate-fat calorie-restricted Mediterranean diet, and a low-carbohydrate non–calorie-restricted diet based on the Atkins diet — in 322 moderately obese adults (mean body-mass index, 31 kg/m2; 86% male). The trial was based at a workplace where lunch (the main meal), tailored to the three diets, was provided in the cafeteria and where study participants met frequently with dieticians.
At 2 years, mean weight loss was significantly greater in the low-carbohydrate and Mediterranean groups than in the low-fat group (4.7 kg and 4.4 kg vs. 2.9 kg). HDL cholesterol levels increased and LDL cholesterol levels remained similar in each group, but the ratio of total cholesterol to HDL cholesterol improved most in the low-carbohydrate group. Among 36 diabetic participants, fasting glucose improved most with the Mediterranean diet. Adherence rates at 2 years were 90%, 85%, and 78% in the low-fat, Mediterranean, and low-carbohydrate groups, respectively. Only 16% of participants withdrew from the trial.
Comment: The authors draw a reasonable conclusion from these results: Because low-carbohydrate and Mediterranean diets are effective alternatives to traditional low-fat diets, any of them can be offered and individualized depending on patient preferences and metabolic needs. This trial, given its relatively long duration and high adherence rate, is an important addition to the literature. However, the results have limited generalizability, because the study was workplace-based and quite labor-intensive.
— Allan S. Brett, MD
Published in Journal Watch General Medicine July 29, 2008
Shai I et al. Weight loss with a low-carbohydrate, Mediterranean, or low-fat diet. N Engl J Med 2008 Jul 17; 359:229.