"I come from Des Moines. Somebody had to."
The story is titled 'Fat Girls in Des Moines', by Bill Bryson. It's one of 21 stories in the Granta Book of Travel, a marvelous book on different places and experiences. Think of the finest travel writers; they're all in here, though Pico Iyer and William Dalrymple aren't. When you find it, weigh it in your hands, and feel your pleasure double. It's distributed by Rupa. Easily available if you ask.