Lifestyle choices,including diet,are conducive to healthy body weights in children. Dairy products and calcium supplementation have been associated with moderation of body weight and body fat. This study was designed to test the following hypotheses with overweight and obese adolescents consuming a controlled diet: - Dietary calcium supplementation as calcium carbonate or dairy calcium modulates energy balance in adolescents. - Increased calcium in the diet of adolescents will increase fecal fat excretion and thereby decrease fat absorption. - Calcium and dairy product supplementation will increase lipid oxidation resulting in an increase in energy expenditure.

Subjects will consume a controlled diet containing 800 mg calcium for two three week periods. During one period they will also receive a frozen ice cream like product (smoothie) twice a day based on soy protein that contains no additional calcium. During the other period they will receive a similar product twice a day based on either dairy protein that contains 650 mg calcium or based on soy protein that contains 650 mg calcium as calcium carbonate