Orlistat is a drug that promotes loss of weight by preventing the digestion and absorption of fat in food.

In the intestine, an enzyme called lipase (produced primarily by the pancreas) breaks apart fat in food so that it can be absorbed into the body. Orlistat blocks the action of lipase and thereby prevents the breakup and absorption of fat. Orlistat blocks absorption of about 25% of the fat in a meal. The unabsorbed fat is excreted in the stool.