BPD is a more complex surgery than DS, and it is typically reserved for patients who are very obese or have other health conditions that make them high risk for other weight-loss surgeries.Duodenal Switch (DS) DS is a combination of a restrictive and malabsorptive surgery. The first step of the surgery is to remove about 80% of the stomach. This reduces the amount of food that you can eat and helps you feel full sooner. The second step of the surgery is to bypass a large portion of the small intestine. This means that your body will not absorb as many calories and nutrients from the food that you eat. Biliopancreatic Diversion (BPD) BPD is a purely malabsorptive surgery. The stomach is not bypassed or removed, but a large portion of the small intestine is bypassed. This means that your body will not absorb as many calories and nutrients from the food that you eat. BPD is a more complex surgery than DS, and it carries a higher risk of complications.