Objective: Studies suggest that high-dairy and high-fiber/low-glycemic index diets may facilitate weight loss, but data are conflicting. The effects on weight loss and body fat of a high-dairy diet and a diet high in dairy and fiber and low in glycemic index were compared with a standard diet.
Research Methods and Procedures: Ninety obese subjects were recruited into a randomized trial of three diets designed to provide a calorie deficit of 500 calories/d over a 48-week period. The study compared a moderate (not low)-calcium diet with a high-calcium diet.
Results: Seventy-two subjects completed the study. Significant weight and fat loss occurred with all three diets. A diet with 1400 mg of calcium did not result in greater weight (11.8 ± 6.1 kg) or fat (9.0 ± 6.0 kg) loss than a diet with 800 mg of calcium (10.0 ± 6.8 and 7.5 ± 6.6 kg, respectively). A diet with 1400 mg of calcium, increased fiber content, and fewer high-glycemic index foods did not result in greater weight (10.6 ± 6.8 kg) or fat (8.5 ± 7.8 kg) loss than the standard diet with 800 mg of calcium. Lipid profile, high-sensitivity C-reactive protein, leptin, fasting glucose, and insulin improved significantly, but there were no significant differences between the experimental diets and the control diet.
Discussion: We found no evidence that diets higher than 800 mg of calcium in dairy products or higher in fiber and lower in glycemic index enhance weight reduction beyond what is seen with calorie restriction alone.