This is not true according to Garrow because people who are taking orlistat will react negatively to a high fat intake. That is, they will probably experience some form of gastrointestinal upset. Like any drug, there are side effects associated with taking Orlistat. Because of these side effects, orlistat is said to change weight by changing behavior. Orlistat changes behavior through a learned aversion response.
People learn that when they eat foods with high fat content, they always get diarrhea.
Eventually, these people will learn to avoid such foods, thus decreasing their calorie intake, which leads to weight loss. This technique is also exhibited in people who take pills to quit smoking. When they have a cigarette, they get violently ill and learn to avoid cigarettes to keep from getting ill. Garrow goes on to say that the reason orlistat works is because it causes 30 percent of the fat we eat to be excreted in feces rather than being digested. But the weight loss associated with the drug is due mainly to dietary changes that people make because they are afraid of getting diarrhea.