Dietary Macronutrients and Weight Loss

To test the effectiveness for weight loss and weight maintenance of four diets differing in macronutrient composition: moderate in fat (35 percent energy) with two different protein levels (15 percent and 25 percent), and low in fat (20 percent energy), also with 15 percent and 25 percent protein.

Official Title

Conditions

– Cardiovascular Diseases- Heart Diseases- Obesity

Study Type

Observational

Study Design

Natural History

Further Details

BACKGROUND: Obesity is a growing problem whose importance is reflected in the resources that are expended each year by a large section of the population on weight reduction drugs and therapies. Although numerous weight loss diets are available, there is little agreement in the scientific literature or the lay press as to the amount of fat, protein and carbohydrates that would comprise the most efficacious diet for weight loss and long term weight loss retention. Reliable information about the effectiveness of low calorie diets with low fat/moderate protein, low fat/high protein, moderate fat/moderate protein and moderate fat/high protein to be examined in this study is clearly needed and of paramount importance to the informed choice of a weight reduction diet. DESIGN NARRATIVE: The study tests the effectiveness for weight loss and weight maintenance of four diets differing in macronutrient composition: moderate in fat (35% energy) with two different protein levels (15% and 25%), and low in fat (20% energy), also with 15% and 25% protein. The moderate-fat diet will be patterned after a Mediterranean diet. All four dietary approaches will be low in saturated fat, and will involve reduction in total energy intake. All participants will receive a state-of-the-art behavioral therapy program standardized across the two centers in Boston and Baton Rouge. The investigators will test the hypothesis that higher baseline insulin, respiratory quotient (RQ) and VO2max will be associated with smaller weight loss and more difficulty maintaining the weight loss during maintenance. Dietary satisfaction and satiety will be assessed as potential predictors of success. An estimated 400 men and 400 women, BMI 27-39 kg/m2, will be randomized among the 4 dietary treatments. Each diet will be developed to be practical and suitable for public health recommendations, and would be expected to have a favorable effect on cardiovascular risk factors. The primary outcome variable will be change in total body weight from baseline to 2 years. Secondary outcomes related to obesity are total body fat, visceral fat mass, BMI, and waist and hip circumferences. Other outcomes include blood pressure, fasting blood lipids, apolipoproteins, insulin, glucose, and hemoglobin A1C.

Study Start

Eligibility & Criteria

Ages Eligible for Study: 20 Years – 65 Years, Genders Eligible for Study: Both Criteria No eligibility criteria

Total Enrolment

Contact Details

[1] Frank Sacks, Harvard University School of Public Health