A consumer group is demanding that Frito-Lay put warning labels on chips with the fat substitute olestra or face a lawsuit by a Massachusetts woman who says she got stomach cramps and had to use the bathroom quickly after eating the snacks. The Center for Science in the Public Interest said Wednesday that 30-year-old Lori Perlow of Braintree, Mass., would sue Frito-Lay under a consumer-friendly deceptive-advertising law in the Bay State. Frito-Lay, a division of PepsiCo Inc., said warning labels are not needed for its Light lines of potato and corn chips. "It's an extremely safe product, well-tested," said Frito-Lay...