Effects of an 8-week high-protein or high-carbohydrate diet in adults with hyperinsulinemia

Context: Incidence of insulin resistance (IR) in Americans is steadily rising. IR may be ameliorated with • 5% loss in body weight. Objective: To examine effects of 2 weight-loss diets on body weight and composition in overweight adults with IR. Design: Participants randomly assigned to a high-protein, low-fat (HPLF) or a high-carbohydrate, low-fat (HCLF) diet for 8 weeks. Setting: All meals prepared and weighed in the metabolic kitchen at Arizona State University. Lunch consumed on-site; all other meals packaged for home consumption. Patients: Twenty overweight, healthy participants with elevated fasting serum insulin (≥ 15 μU/L) were recruited. Interventions: Both diets were low-fat (27% kcal from fat; < 7% saturated, ≤ 10% monounsaturated, and ≤ 10% polyunsaturated) and energy-restricted (energy levels were 1200, 1500, 1700 or 2000 kcal); resting metabolic rate. Main Outcome Measures: Body composition, metabolic indices, fasting plasma glucose, and insulin. Results: No significant differences were found in the main outcome measures between the diets. Body weight (HPLF: -4.9 kg; HCLF: -4.0 kg) and total percent body fat (HPLF: -1.5%; HCLF: -0.4%) significantly reduced from baseline to week 8 (P = .005 and P = .035, respectively). Conclusion: Both diets promoted ≥ 5% loss in body weight and significantly reduced percent body fat.