Understanding the Duodenal Switch gwhqadmin March 2, 2009 Duodenal Switch 2 Comments The Duodenal Switch (DS) is a combination weight loss surgery procedure that is both restrictive and malabsorptive. With the duodenal switch, the size of your stomach is reduced by about 70%, and part of the intestine is also switched around to change how food is digested and limit calorie absorption. This helpful article offers a primer on the duodenal switch, including the advantages and disadvantages of this innovative bariatric procedure.