Obesity and overweight are linked to a wide range of medical conditions, such as hypertension, diabetes mellitus, osteoarthritis, obstructive sleep apnea, and coronary artery disease. Overweight and obese patients who are unable to lose weight with diet alone can benefit from well-structured exercise. Potentially, an individual exercise prescription can become one of the most important components of an obesity treatment program, along with an appropriate diet. Short-term (<6 months of duration) interventions consisting of exercise combined with appropriate diet and counseling can produce a significant weight loss. No consensus exists on the amount of physical activity necessary to maintain the weight loss achieved during a short-term intervention. Long-term intervention is frequently influenced by weight regain related to complex interactions between physiologic and psychosocial factors.