Obesity is a complex, multifactorial condition in which excess body fat may put a person at health risk. National data indicate that the prevalence of obesity in the United States is increasing in children and adults. Reversing these trends requires changes in individual behavior and the elimination of societal barriers to healthy lifestyle choices. Basic treatment of overweight and obese patients requires a comprehensive approach involving diet and nutrition, regular physical activity, and behavioral change, with an emphasis on long-term weight management rather than short-term extreme weight reduction. Physicians and other health professionals have an important role in promoting preventive measures and encouraging positive lifestyle behaviors, as well as identifying and treating obesity-related comorbidities. Health professionals also have a role in counseling patients about safe and effective weight loss and weight maintenance programs. Recent evidence-based guidelines from the National Heart, Lung, and Blood Institute, as well as recommendations from the American Academy of Pediatrics, American Association of Clinical Endocrinologists/American College of Endocrinology, American Obesity Association, U.S. Clinical Preventive Services Task Force, Institute of Medicine, and World Health Organization can be consulted for information and guidance on the identification and management of overweight and obese patients.