Effect of calcium and dairy foods in high protein, energy-restricted diets on weight loss and metabolic parameters in overweight adults

OBJECTIVE: To compare the effects two high-protein (HP) diets that differ in dietary calcium and protein source on weight loss, body composition, glucose and lipid metabolism, markers of liver function, fibrinolysis and endothelial function and blood pressure. DESIGN: Randomized, parallel study (12 wk of energy restriction, 4 wk of energy balance) of high dairy protein/high-calcium (DP, 2400 mg Ca/d) and high mixed protein/moderate calcium (MP, 500 mg Ca/d) diets (5.5 MJ/d, 34% protein, 41% carbohydrate, 24% fat). SUBJECTS: In all, 50 healthy, overweight (age 25-64 y; body mass index 25-35 kg/m(2);) males (n=20) and females (n=30). RESULTS: Loss of total weight (-9.7+/-3.8 kg), fat mass (-8.3+/-0.4 kg) and lean mass (-1.6+/-0.3 kg) were independent of dietary group. Improvements in fasting insulin, lipids, systolic/diastolic blood pressure, and markers of liver function, fibrinolysis and endothelial function were independent of dietary intervention. CONCLUSIONS: Increased dietary calcium/dairy foods in an energy-restricted, HP diet does not affect weight loss or body composition. Weight reduction following increased protein diets is associated with beneficial metabolic outcomes that are not affected by protein source.