This guideline is based on the evidence report and accompanying background papers developed by the Southern California Evidence-Based Practice Center. The American College of Physicians nominated this topic to the Agency for Healthcare Research and Quality Evidence-Based Practice Center program as part of a concerted effort to complement the guidelines of the U.S. Preventive Services Task Force. The College recommends that all clinicians refer to the Task Force recommendations as part of an overall strategy for managing overweight and obesity, which should always include appropriate diet and exercise for all patients who are overweight or obese. The intent of this guideline is to provide recommendations based on a review of the evidence on pharmacologic and surgical treatments of obesity. The target audience is all clinicians caring for obese patients, defined as a body mass index of 30 kg/m2 or greater. This guideline is not intended to be used by commercial weight loss centers or for direct-to-consumer marketing by manufacturers and does not apply to patients with body mass indices below 30 kg/m2.