Severe obesity is a chronic condition that is hard to treat with diet and exercise alone. Bariatric surgery is an operation on the stomach and/or intestines that helps patients with extreme obesity to lose weight. This surgery is an option for people who cannot lose weight by other means or who suffer from serious health problems related to obesity. The surgery restricts food intake, which promotes weight loss and reduces the risk of type 2 diabetes. Some surgeries also interrupt how food is digested, preventing some calories and nutrients, such as vitamins, from being absorbed. Recent studies suggest that bariatric surgery may even lower death rates for patients with severe obesity. The best results occur when patients follow surgery with healthy eating patterns and regular exercise.