Orlistat is a medication used for weight loss and weight management. It is sold under the brand names Xenical and Alli. It works by blocking the action of the enzyme lipase, which breaks down dietary fat into smaller molecules that can be absorbed by the body. This means less fat is absorbed from the intestine and the body’s own fat stores must be used. Orlistat has been shown to reduce body weight by an average of 5-10% after twelve months of treatment. Orlistat has been proven to be safe and effective in helping to manage weight. However, it is important to remember that it should not be used as a replacement for healthy eating and physical activity. It is intended to be part of a comprehensive weight-loss and weight-management plan. Common side effects of orlistat include stomach pain, diarrhea, and headaches. When used alongside a healthy diet, orlistat has been found to be generally safe and well-tolerated, with a low risk of serious side effects.