Olestra, brand name olean® , is a non-absorbable, non-digestible, fat substitute that contributes zero calories to the diet. In 1996, the Food and Drug Administration approved olestra as a macro-ingredient food additive in savory snacks. Olestra can replace up to 100% of the fats and oils used in the preparation of these foods. Consumer advocacy groups and members of the scientific community find olestra's presence in the consumer market appalling. There are numerous claims and studies that show that moderate consumption of olestra may result in gastrointestinal discomfort, such as abdominal cramps, diarrhea, nausea, and "anal leakage". Olestra also decreases the absorption of fat-soluble nutrients (carotenoids, vitamins A, D, E, and K) by the body. Despite the negative effects on the gastrointestinal system and lipophilic nutrient absorption, olestra has some potential benefits. The non-digestible, non-absorbable property of olestra accounts for its zero calorie contribution to the diet. Olestra can be used as an aid in weight reduction; can limit and or reduce dietary fat consumption without compromising caloric intake; reduce caloric intake; and help at risk populations to more closely follow recommended dietary guidelines. This paper assesses olestra's effect on vitamin absorption, gastrointestinal system, and daily energy intake and fat reduction.