Competitive eaters aren't just good at stuffing their faces: Their digestive systems actually function differently from everyone else's. A researcher at the University of Pennsylvania compared the eating habits of a leading competitive eater and a man who weighed 45 pounds more than the champion did. He scanned the two men's stomachs during a hot-dog-eating contest.
Normally, the digestive tract makes "wavelike" contractions, even when there's no food in it. The process, called peristalsis, pushes food through the body, Popular Science explains. But the competitive eater's body showed hardly any peristalsis, even after he'd eaten 36 hot dogs. His stomach behaved "more like an expanding balloon than a squeezing sac," writes Bette Marston; it grew to nearly fill his upper abdomen. The champion's stomach had adapted to his frequent eating beyond being full in a process experts don't fully understand.