Does Alli Work?

Alli promotes weight loss by decreasing absorption of fat by the intestines, which reduces the number of calories you absorb. Lipase, an enzyme found in the digestive tract, helps break down dietary fat into smaller components, so it can be used or stored for energy. Alli works by disabling lipase, which prevents the enzyme from breaking down the fat while it's in your digestive tract. The undigested fat continues through the intestines and is eliminated through bowel movements. Alli is taken with fat-containing meals, up to three times a day. Because of how Alli works, it's recommended that you eat no more than 15 grams of fat with each meal. Eating higher amounts of fat can cause unwanted effects, such as urgent bowel movements, diarrhea and gas with oily spotting.