Duodenal Switch (also known as biliopancreatic diversion with duodenal switch - BPD-DS, or gastric reduction duodenal switch - GRDS) is a weight loss surgery that is carried out to restrict the size of the stomach and therefore reducing the amount of food that can be eaten and absorbed by the body. Around 85% of the stomach is removed, however the nerves to the stomach and the outlet valve are not altered, therefore the function of the stomach remains.
The intestines are also split up into pathways so that food can be separated from the digestive juices. This is done to create malabsorption which prevents the patient from absorbing all the calories that are eaten. As a result, patients that have undergone this procedure only absorb around 20% of the fat that they intake.