Although still considered more of a cosmetic problem by both the general public and some areas of the medical community, overweight and obesity have reached epidemic proportions worldwide. Overweight and obesity have not only a significant psychological impact but also result in an increased risk for development of numerous chronic and sometimes fatal diseases. The morbidity from obesity-associated disorders increases with higher body mass index and begins within the normal weight range. The costs (direct and indirect) associated with treating obesity and its comorbid conditions are notable and increasing. Obesity rates in patients with schizophrenia are at least as high, if not higher, than in the general population. This article reviews the epidemiology and burden of obesity and its associated comorbid disorders. The guidelines from the National Heart, Lung, and Blood Institute of the National Institutes of Health for diagnosing and treating obesity are also discussed.