POPULAR DIETS, METABOLISM, AND CVD RISK

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Specific Aim #1: To evaluate the effects of three dominant diets - conventional low-fat, low-fat/low-glycemic index and very-low-carbohydrate - on energy expenditure following weight loss in obese young adults Hypotheses: 1a Energy expenditure following weight loss will be lower during the conventional low-fat diet compared to either the low-fat/low-glycemic index diet or the very-low-carbohydrate diet. 1b Resting and total energy expenditure will not differ between the low-fat/low-glycemic index diet and the very-low-carbohydrate diet. Primary endpoint: resting energy expenditure using indirect calorimetry in the fasting state. Secondary endpoints: total energy expenditure using doubly labeled water methodology; thermic effect of food using indirect calorimetry; physical activity using accelerometry. Specific Aim #2: To evaluate the effects of three dominant diets on other physiological adaptations to weight loss in obese adults Hypotheses: 2a Changes from baseline in physiological adaptations to weight loss will be greater during the conventional low-fat diet compared to either the low-fat/low-glycemic index diet or the very-low-carbohydrate diet. 2b Changes in the physiological adaptations to weight loss will not differ between the low-fat/low-glycemic index diet and the very-low-carbohydrate diet. Primary endpoint: serum T3 concentration. Secondary endpoints: Other thyroid functions (T4, reverse T3, TSH, THBG), measures of growth hormone action (IGF-1), reproductive hormones (LH, FSH, testosterone, estradiol), stress hormones (24-hr urinary cortisol), hunger. Specific Aim #3: To evaluate the effects of three dominant diets on cardiovascular disease risk factors following weight loss in obese young adults. Hypotheses: 3a Insulin resistance will be lower (greater insulin sensitivity) during the low-fat/low-glycemic index diet compared to either the very-low-carbohydrate diet or the conventional low-fat.