WASHINGTON: The Food and Drug Administration approved the controversial fat substitute olestra. "This product is an example of the country's never-ending quest to have their fat and eat it, too," says medical writer Christine Gorman. "But as with all promises that you can get something for nothing, it is too good to be true. Moderation is the key. If people eat products made with olestra along with a sensible diet, then they should be fine. Besides, the side effects of diarrhea and other gastrointestinal problems kind of give olestra a built in safety valve against overeating its products." Olestra, which is produced by Procter & Gamble, was approved to be used in snack foods, provided that a warning of possible side effects is on the label.