It is hypothesized that the use of a partial supplement diet, which includes the use of meal replacements, will result in significantly greater weight loss after three and six months compared to an isocaloric diet that does not include supplements. It is also hypothesized that the partial supplement diet will result in larger improvements in body composition, disease biomarkers, and health parameters (blood pressure, lipids) compared to the non-supplement diet. Finally, it is hypothesized that subjective ratings of satiety will be significantly higher, and ratings of hunger lower, in the group consuming a partial supplement diet.