What is the mechanism of action for orlistat?

Orlistat works primarily by blocking fat absorption in the gastrointestinal tract. It inhibits the action of lipases, enzymes that are essential for the breakdown of dietary fats into absorbable free fatty acids and monoglycerides. When lipases are inhibited, the dietary fats consumed in a meal remain undigested and become excreted without being absorbed into the body. This mechanism leads to a reduction in caloric intake from fat, contributing to weight loss in individuals who are overweight or obese.

The other options do not accurately describe the primary function of orlistat. For example, enhancing appetite control, boosting metabolic rate, and increasing thermogenesis refer to different pharmacological actions that are not part of how orlistat functions. Instead, its effectiveness lies specifically in its ability to prevent the absorption of dietary fats, making it a unique weight management medication. This characteristic is what distinguishes it from other weight loss interventions that may focus on appetite suppression or metabolic enhancement.