The first study aim is (1) to test, in a randomized controlled trial, whether provision of portion-controlled prepackaged lunch and dinner entrees in the context of a reduced-energy diet prescription and counseling is associated with a greater degree of weight loss at 12 weeks in overweight or obese men and women, compared to usual care or control conditions in which the prescribed reduced-energy diet is to be consumed via self-selected foods. This study utilizes a randomized study design with participants assigned to the prepackaged food intervention arms or a usual care control group. The second study aim is (2) to describe the effect of participation in the prepackaged food arms (versus control conditions) on circulating lipids (fasting total plasma cholesterol and triglycerides, low-density lipoprotein [LDL] cholesterol, and high-density lipoprotein [HDL] cholesterol), carotenoids (a biomarker of vegetable and fruit intake), C-reactive protein, and cardiopulmonary fitness.