This review of current medical knowledge about the etiology, evaluation, medical, and pharmacologic treatment of obesity suggests patient care strategies emphasizing office evaluation and treatment. Office assessment of obesity, which is the consequence of multiple genetic, neurohormonal, environmental, and behavioral factors, should include a careful chronological history with calculation of body mass index and a focused examination. Treatment consideration should be given to recommendations about calorie intake, but debate continues over the ideal macronutrient composition. Other treatment recommendations for successful weight loss and maintenance include a high level of physical activity, behavior modification programs that improve adherence to diet and exercise, and pharmacologic therapy. Obesity is an increasingly prevalent medical problem in the United States that is best treated using a multidisciplinary approach. Medical providers require the most up-to-date information in order to provide their patients with a multifaceted approach to successful weight loss and lifelong weight maintenance.