You need to eat about 15 grams of fat with your meals while taking alli.  alli works by inhibiting some of the body’s absorption of dietary fat. Taken at meal times, it works by blocking the absorption of about 25 percent of fat in the food a person eats.   Because of the way it works, alli must be used in conjunction with a reduced-calorie, low-fat diet containing about 15 grams of fat per meal.  Eating a meal with too much fat while taking alli can result in bowel changes, such as loose stools, more frequent stools that may be hard to control, or gas with oily spotting.  These changes, called treatment effects, generally occur for the first time in the first weeks of treatment, are not harmful, and can generally be managed by following the recommended diet with about 15 grams of fat per meal. 

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