Obesity is a chronic condition, and long-term treatment will most likely be needed. Approved prescription medications for weight loss appear to have similar efficacy in controlled studies. No predictors of responsiveness in an individual patient or class of patients have been established. The choice of a medication is based on the underlying medical indication or contraindication of a particular drug, concurrent medication, age of the patient, need for monitoring, anticipation of the length of therapy, and the preference of a patient. Behavioral and dieting interventions, and increased physical activity are considered the primary means to promote and maintain weight loss. Weight-loss medications should be considered only as an adjunct for patients who are at substantial risk because of their obesity and in whom non-pharmacologic treatments have not resulted in sufficient weight loss to improve health or to prevent weight regain.