No more. Last September the former marketing executive opened F3, a 4,300-sq.-ft. grocery store on Manhattan's East Side, a one-stop fat-free emporium where the aisles are filled with guiltless goodies—and lots of excited customers. "Normally when I walk into a supermarket, there's a battle between my id and my superego, with usually the id winning out," says psychiatrist Isaac Herschkopf, 50, who loves the store's healthful cheesecakes and dried fruit. "When I walk into F3, there's no struggle."
Growing up in Great Neck, N.Y., the older child of dermatologist Harvey Moser, 71, and his wife, Harriet, 59, a Ph.D. student, Halperin herself never struggled with weight but takes her customers' battles seriously. Every item she stocks must contain less than half a gram of fat per serving (the FDA requirement for "fat-free" foods)—and pass her personal taste test. "If I don't like it, I don't have it," says Halperin, who lives in Manhattan with her dermatologist husband, Peter, 38. It has been worth the effort for both Halperin—who expects sales of $1.5 million this year—and her customers. "I've gotten hugs from people," she says. "They get the feeling they're in a candyland. They say, 'Thank you so much for this store. This is what I've always wanted.' "
An avid runner and biker since her teens, Andrea Halperin has always kept to a low-fat diet. But in recent years, as eating trends shifted toward high-protein, low-carbohydrate regimens, she noticed that her favorite fat-free foods were being crowded off supermarket shelves. "I had to go to four different stores to find what I wanted," says Halperin, 34. "It was annoying."