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

Mar 01, 2009
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Author/Summarized by Author:
Anthony A. Bavry, MD, MPH, FACC
Summary Reviewer:
Deepak L. Bhatt, MD, MPH, MBA, FACC
Trial Sponsor:
National Heart, Lung, and Blood Institute and the General Clinical Research Center, National Institutes of Health
Date Published:
01/01/2009
Date Updated:
03/01/2009
Original Posted Date:
03/01/2009
References

Description:

The goal of the trial was to compare the effect of different proportions of dietary macronutrients on weight loss and reduction in waist circumference.

Hypothesis:

A certain type of diet may be associated with increased weight loss.

Study Design

  • Randomized
  • Blinded
  • Parallel

Patients Screened: 1,638
Patients Enrolled: 811
Mean Follow Up: 2 years
Mean Patient Age: 51 years
Female: 64%

Patient Populations:

  • Overweight and obese patients (body mass index 25-40 kg/m2)
  • 30-70 years of age

Exclusions:

  • Diabetes or unstable cardiovascular disease
  • Use of weight loss medication
  • Insufficient motivation, as assessed by the interviewer

Primary Endpoints:

  • Change in body weight over 2 years

Secondary Endpoints:

  • Change in waist circumference over 2 years

Drug/Procedures Used:

Overweight adults were randomized to one of four diets, based on proportion of fat, protein, and carbohydrates: 1) low-fat, average-protein (n = 204); 2) low-fat, high-protein (n = 202); 3) high-fat, average-protein (n = 204); and 4) high-fat, high-protein (n = 201). Similar foods were used in all diets.

Principal Findings:

Overall, 811 overweight and obese patients were randomized, and 645 (80%) completed the study. The mean age was 51 years, 64% were women, mean body mass index was 33 kg/m2, mean waist circumference was 103 cm, hypertension was present in 35%, and mean low-density lipoprotein (LDL) cholesterol was 126 mg/dl.

Among all participants over the duration of follow-up, mean weight loss was 3.6 kg for the high-protein group and 3.0 kg for the low-protein group (p = 0.22). Similarly, mean weight loss was 3.3 kg for the high-fat group and 3.3 kg for the low-fat group (p = 0.94). Among those who completed the study, the amount of weight loss was greater (mean 4 kg), although there was no difference between the diets. Most weight loss occurred in the first 6 months, and then trended up for the remainder of follow-up.

There was no change in waist circumference according to protein intake (p = 0.22), fat intake (p = 0.99), or carbohydrate intake (p = 0.39).

The decrease in LDL cholesterol over follow-up was 5.9% for the low-fat, average-protein diet; 3.9% for the low-fat, high-protein diet; 0.2% for the high-fat, average-protein diet; and 1.3% for the high-fat, high-protein diet. Satiety, satisfaction, and hunger were similar between all the diets.

Interpretation:

Among overweight patients, a reduced calorie diet was principally important for long-term weight loss and not the proportion of fat, protein, and carbohydrates in the diet. There was similar weight loss and reduction in waist circumference with all the diets. Most weight loss occurred at 6 months and then trended up over the remainder of follow-up. LDL cholesterol was reduced the most with the low-fat, average-protein diet; however, it is unknown if this would translate into greater long-term cardiovascular benefit.

Up until now, limited data existed for recommending a certain dietary percentage of macronutrients. This randomized trial revealed that any of the four experimental diets were well tolerated, had similar satisfaction and hunger, and produced the same degree of weight loss and reduction in waist circumference.

References:

Sacks FM, Bray GA, Carey VJ, et al. Comparison of weight-loss diets with different compositions of fat, protein, and carbohydrates. N Engl J Med 2009;360:859-73.

Keywords: Hunger, Cholesterol, Waist Circumference, Body Mass Index, Overweight, Weight Loss, Personal Satisfaction, Obesity, Diet, Reducing, Weight Gain, Hypertension


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