Comparison of Weight-Loss Diets With Different Compositions of Fat, Protein, and Carbohydrates

Abstract

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. (ClinicalTrials.gov number, NCT00072995.

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“…It has been shown that similar responses regarding satiety, hunger and satisfaction exist for diets with different proportion of nutrients (44) . In general, the reduced-energy diets result in clinically meaningful weight losses regardless of which macronutrients they emphasise (36)(37)(38)(39)(40)(41)(42)(43)(44) . For long-term weight loss, macronutrient composition should also be considered regarding whether it helps to counteract compensatory mechanisms leading to weight regain after weight loss (45) .…”

Is cooking at home associated with better diet quality or weight-loss intention?

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“…A key question is the longterm response to diets that emphasise a specific macronutrient profile. In a recent large trial 811 overweight adults were assigned to one of four diets to enable comparisons of low fat v. high fat, average protein v. high protein and over a range of carbohydrate intake (63) . Across the 2 years of follow-up the subjects were offered group and individual dietary instructional sessions.…”