dx keto This surgery has fewer risks than bypass , but the results are less satisfactory, allowing you to lose about 40% of the initial weight, being very similar to the gastric band.4. Biliopancreatic bypassBariatric surgery: what it is, types, advantages and risks This surgery is the least frequent, applying both a restrictive and malabsortive surgical technique, a gastric sleeve is performed first, leaving the stomach in the form of a tube and a large part of the small intestine is removed, reducing the absorption of nutrients and therefore the calories that enter the body.