Olestra (olean)

Fat substitute: Lay's Light Chips, Pringles Light chips.
Olestra is Procter & Gamble’s synthetic fat that is not absorbed as it passes through the digestive system, so it has no calories. Procter & Gamble suggests that replacing regular fat with olestra will help people lose weight and lower the risk of heart disease. Originally envisioned as a replacement for fat in everything from cheese to ice cream, the ingredient is now only used in a couple of brands of snack chips. 

Olestra can cause diarrhea and loose stools, abdominal cramps, flatulence, and other adverse effects. Those symptoms are sometimes severe. 

Olestra reduces the body's ability to absorb fat-soluble carotenoids (such as alpha and beta-carotene, lycopene, lutein, and canthaxanthin) from fruits and vegetables, but an occasional serving wouldn't be a problem. Those nutrients are thought by many experts to reduce the risk of cancer and heart disease. Olestra enables manufacturers to offer greasy-feeling low-fat snacks, but consumers would be better off with baked snacks, which are safe and just as low in calories. Products made with olestra should not be called "fat free," because they contain substantial amounts of indigestible fat.