BACKGROUND The possible advantage for weight loss of a diet that emphasizes protein, fat, or carbohydrates has not been established, and there are few studies that extend beyond 1 year. METHODS We randomly assigned 811 overweight adults to one of four diets; the targeted percentages of energy derived from fat, protein, and carbohydrates in the four diets were 20, 15, and 65%; 20, 25, and 55%; 40, 15, and 45%; and 40, 25, and 35%. The diets consisted of similar foods and met guidelines for cardiovascular health. The participants were offered group and individual instructional sessions for 2 years. The primary outcome was the change in body weight after 2 years in two-by-two factorial comparisons of low fat versus high fat and average protein versus high protein and in the comparison of highest and lowest carbohydrate content. RESULTS At 6 months, participants assigned to each diet had lost an average of 6 kg, which represented 7% of their initial weight; they began to regain weight after 12 months. By 2 years, weight loss remained similar in those who were assigned to a diet with 15% protein and those assigned to a diet with 25% protein (3.0 and 3.6 kg, respectively); in those assigned to a diet with 20% fat and those assigned to a diet with 40% fat (3.3 kg for both groups); and in those assigned to a diet with 65% carbohydrates and those assigned to a diet with 35% carbohydrates (2.9 and 3.4 kg, respectively) (P>0.20 for all comparisons). Among the 80% of participants who completed the trial, the average weight loss was 4 kg; 14 to 15% of the participants had a reduction of at least 10% of their initial body weight. Satiety, hunger, satisfaction with the diet, and attendance at group sessions were similar for all diets; attendance was strongly associated with weight loss (0.2 kg per session attended). The diets improved lipid-related risk factors and fasting insulin levels. CONCLUSIONS Reduced-calorie diets result in clinically meaningful weight loss regardless of which macronutrients they emphasize.

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BACKGROUND Weight loss is recommended for overweight and obese individuals with type 2 diabetes based on short-term studies, but long-term effects on cardiovascular disease remain unknown. We examined whether intensive lifestyle intervention for weight loss decreased cardiovascular morbidity and mortality in overweight or obese adults with type 2 diabetes. METHODS We randomly assigned 5,145 overweight or obese individuals with type 2 diabetes recruited at 16 US centers to intensive lifestyle intervention (the intervention group), which promoted weight loss through decreased calorie intake and increased physical activity, or diabetes support and education (the control group). The primary outcome was the first post-randomization occurrence of a composite cardiovascular outcome (cardiovascular death, non-fatal myocardial infarction, non-fatal stroke, or hospitalized angina) over a planned maximum follow-up of 13.5 years. RESULTS The trial was stopped early based on a futility analysis when median follow-up was 9.6 years. Weight loss was greater in the intervention group than the control group throughout (8.6% vs. 0.7% at 1 year; 6.0% vs. 3.5% at study end). Intensive lifestyle intervention also produced greater reductions in hemoglobin A1c and greater initial improvements in fitness and all cardiovascular risk factors, except LDL cholesterol. The primary outcome occurred in 403 patients in the intervention group and in 418 in the control group (1.83/100 person-years and 1.92/100 person-years, respectively; hazard ratio 0.95; 95% CI 0.83 to 1.09, p=0.505). CONCLUSION In our study, intensive lifestyle intervention focused on weight loss did not reduce cardiovascular events in overweight or obese adults with type 2 diabetes. (Funded by the Department of Health and Human Services and others; ClinicalTrials.gov number, NCT00017953.)