Olestra was set to be a miracle food when it appeared in the 1990s, a fat-free substance that could take the place of real fat in snacks foods, thus allowing you to eat like some manner of Hutt while never growing to vast Porkins proportions. The FDA approved olestra in 1996 because it seemed pretty much super safe for humans.
Among the super-safe side effects of olestra was a five-fold increase in diarrhea compared to people eating natural fats. During one eight-week study, subjects who ate 32 grams of Olestra per day, the amount you'd get in 3 ounces of chips, were running an even gamble on the squirts -- a full half of participants ended up with diarrhea.
Olestra's big side effect in terms of sex appeal was anal leakage and staining of the underwear. Thanks to greasy, hard-to-wipe fecal matter (I didn't even choose those words, that's like a scientific observation), eating olestra could lead to back door streakage. Plus it had the potential for leakage of greasy ass resin out of the ol' sphincter. It's a pretty unwholesome package when you put it all together, and it basically suggests that olestra, while fat- and calorie-free, was going to make you shit yourself one way or another. No fat goes in, something is definitely coming out.
Canada ending up banning olestra, as did several European countries, thanks to Proctor & Gamble not being able to prove that it was particularly safe. This, accompanied by the widespread news that eating it would make you drop an oily horror in your trousers, pretty much killed the product completely, although you can still hunt it down if you're in the mood for a well-lubricated snack food experience.