Obesity is a global epidemic posing serious threats to public health. Knowledge about obesity is especially important for gastroenterologists because of the many gastrointestinal comorbidities of the disease and the numerous gastrointestinal side effects and complications of most methods of treatment-from diet to drugs to antiobesity surgery. Bariatric surgery has improved dramatically through availability of laparoscopic approaches at the same time as the lack of efficacy of nonsurgical treatment for moderate to severe obesity has become apparent. Patient education and selection is critical.