Medications How the alli Weight Loss Medication Helps You Slim Down By Jennifer R. Scott Jennifer R. Scott is a weight loss writer. She designed her own successful weight loss plan, which helped her safely lose 50 pounds in about a year. Learn about our editorial process Jennifer R. Scott Medically reviewed by Medically reviewed by Richard Fogoros, MD on February 08, 2016 Richard N. Fogoros, MD, is a retired professor of medicine and board-certified internal medicine physician and cardiologist. He is Verywell's Senior Medical Advisor. Learn about our Review Board Richard Fogoros, MD Updated on October 02, 2019 Print GlaxoSmithKline Are you looking for a weight loss medication to suppress your appetite? Many diet pills help you eat less by decreasing your hunger or boosting energy levels. But alli diet pills work differently as alli does not affect your appetite. How alli Diet Pills Work The over-the-counter medication alli (orlistat) is FDA-approved as a lipase inhibitor. That means that the weight loss medication blocks some dietary fat from being absorbed into your body. The fat that is not absorbed into your body is eliminated in your stool. When less fat is absorbed and stored by your body, it may become easier to slim down. Alli is not designed to have any effect on your powerful hunger hormones or on your feelings of hunger or food cravings throughout the day. Instead, alli works in the digestive system. If you take alli for weight loss, you're still likely to feel the urge to eat often or eat the wrong foods. In addition, alli does not claim to decrease fatigue as many diet pills do. It is not an amphetamine, so the diet pill does not have any direct effect on your nervous system or heart. It does not boost your energy levels when you're trying to lose weight. How Alli Works to Help You Lose Weight Is alli the Right Diet Pill for You? Alli is designed to help adult dieters with a BMI of 25 or over who are ready to commit to a low-calorie, low-fat eating plan. Before you consider alli to lose weight, you should carefully examine the side effects, costs and potential benefits of the medication. alli works for some dieters but may not be right for everyone. For example, if you take alli, you have to watch your diet very carefully. Even though the weight loss medication helps your body eliminate fat, you can't eat more fat as a result. In fact, you need to eat less fat. If you don't, the side effects can be severe. Experts recommend that you consume fewer than 30 percent of your daily calories from fat and eat no more than 15 grams of fat in any single meal. If you eat more fat than recommended while taking alli, you may experience difficulty controlling your bowel movements, oily stool, and stomach problems. These side effects may be embarrassing or uncomfortable, especially in social settings. How to Find the Right Diet Pill Before you consider any diet pill, you should evaluate your diet history and your weight loss barriers. You should also talk to your doctor about weight loss. alli is available over the counter, so no prescription is necessary. But that doesn't mean that anyone should take it. Certain dieters, including those who have had an organ transplant, who have cholestasis or malabsorption syndrome are often advised not to take alli. Dieters who struggle with hunger should also be cautious about taking alli. If you have gained weight or have trouble losing weight because you have difficult food cravings, alli may not help. Since alli does not suppress appetite, you may not get the weight loss help you need from this pill. Was this page helpful? Thanks for your feedback! Get one simple hack every day to make your life healthier. Sign Up You're in! Thank you, {{form.email}}, for signing up. There was an error. Please try again. What are your concerns? Other Inaccurate Hard to Understand Submit Article Sources Verywell Fit uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. alli. GlaxoSmithKline Consumer Healthcare. Medline Plus. Orlistat. U.S. National Library of Medicine.