Olestra is a fat-free, non-caloric fat substitute that became popular in the 1990s as a way to lower fat in processed foods such as potato chips. It fell out of favour in the US within a few years but is still available in some fat-free and light products.
Olestra is resistant to digestion and can cause cramping and loose, oily stools due to an excess of fat in stool. This is particularly prevalent when consuming more than one serving of a product. Olestra also inhibits absorption of some vitamins and micronutrients.
Olestra is not approved for use in Canada or the EU.
Chips, cookies, processed foods with reduced fat
U.S. Food and Drug Administration
U.S. Food and Drug Administration 2