Alli weight-loss pill: Does it work?

Is Alli the solution to your weight-loss woes? A Mayo Clinic specialist discusses the effectiveness of Alli, an over-the-counter weight-loss pill. By Mayo Clinic Staff

Alli (pronounced AL-eye) is meant for overweight adults who are struggling to shed excess pounds. With its easy access and weight-loss promises, is Alli your answer to losing weight permanently?

Here, Donald D. Hensrud, M.D., a preventive medicine and nutrition specialist at Mayo Clinic, Rochester, Minn., answers common questions about Alli.

What is Alli?

Alli is the reduced-strength version (60 milligrams vs. 120 milligrams) of orlistat (Xenical), a prescription drug to treat obesity. It's approved for over-the-counter sale to overweight adults 18 years and older. Alli is meant to be used in conjunction with a low-calorie, low-fat diet and regular exercise.

What are the concerns with Alli?

In 2009, the Food and Drug Administration (FDA) began a safety review of orlistat because of rare reports of serious liver injury in people using it. The FDA found no cause-and-effect relationship between orlistat and the risk of liver injury. However, Alli and Xenical labels now advise people to be alert to signs and symptoms that could indicate liver injury, such as itching, loss of appetite, yellow eyes or skin, light-colored stool, or brown urine.

How does Alli work?

Alli promotes weight loss by decreasing absorption of fat by the intestines, which reduces the number of calories you absorb.

Lipase, an enzyme found in the digestive tract, helps break down dietary fat into smaller components, so it can be used or stored for energy. Alli works by disabling lipase, which prevents the enzyme from breaking down the fat while it's in your digestive tract. The undigested fat continues through the intestines and is eliminated through bowel movements.

Alli is taken with fat-containing meals, up to three times a day. Because of how Alli works, it's recommended that you eat no more than 15 grams of fat with each meal. Eating greater amounts of fat can cause unwanted effects, such as urgent bowel movements, diarrhea and gas with oily spotting.

How much weight could I lose using Alli?

Alli can help you lose weight, but the weight loss will likely be modest — perhaps just a few pounds more than you would lose with diet and exercise alone.

The average weight loss for prescription-strength Xenical is about 5 to 7 pounds (about 2 to 3 kilograms) greater than diet and exercise alone after one year. (2, 4) The lower dose Alli could conceivably result in a loss of 3 to 5 pounds (about 1 to 2 kilograms) a year in addition to the weight loss you could expect from diet and exercise alone.

Feb. 11, 2012 See more In-depth