In recent decades, the prevalence of obesity has increased dramatically in the United States. Obesity has been associated with an increased risk of the metabolic syndrome, which is characterized by a cluster of metabolic derangements, including insulin resistance, high blood sugar, high triglycerides, low high density lipoprotein (HDL) cholesterol levels, high blood pressure, and inflammation. Lifestyle interventions, including dietary modification, physical activity, and weight loss, form the basis of treatment for individuals with the metabolic syndrome. However, the optimal composition of the diet is not known at this time. Furthermore, due to hormonal and metabolic changes that accompany weight loss, most people find it very difficult to maintain significant weight reductions over time. As a result, weight regain is exceedingly common.