The purpose of this report is to propose standards for the successful treatment of obesity. This process is somewhat arbitrary because obesity is a multifactorial disease and because standards need revision as diagnostic and treatment techniques improve. Weight loss, the classic standard of success, does not account for individual variability. Reduction in other measures of body size, such as body mass index, percentage of excess weight, and body fat, may be preferable. Improvement in known complications of obesity (diabetes mellitus, hypertension, hyperlipoproteinemia, sleep apnea, and psychosocial problems) are equally valid measures of success. Because obesity is a chronic disease, maintenance of weight loss is included as a standard of success. Response to obesity treatment varies, and thus criteria to define minimal, intermediate, and full success for each variable are necessary.