Lipase inhibition, leading to decreased intestinal fat adsorption can be used in the treatment of obesity. Orlistat, a lipase inhibitor, in a dose of 50 mg three times a day leads to a significant increase in weight loss compared to placebo in moderately obese people. These results are confirmed in a multiple-dose study using 10 mg, 60 mg and 120 mg Orlistat three times a day vs. placebo. The use of lipase inhibition has no significant influence on fasting levels of several hormonal systems, including thyroid hormones, catecholamines and IGF-I. The same is true for the responses of several gastrointestinal and pancreatic hormones after a liquid high-fat mixed meal. In general, Orlistat is tolerated very well, although a higher occurrence of gastrointestinal side effects is seen.