The purpose of the proposed study is to test the effect of a partial supplement diet on body weight, body composition, and biomarkers for disease compared to an isocaloric diet that consists of a traditional food-based meal plan. Overweight and obese (BMI 25 to 35) participants will participate in this six-month study. The primary outcome variable is body weight loss and the secondary outcome variables include body composition, blood pressure, lipids, and subjective ratings of satiety.