"Radiology of Competitive Speed Eating":

...[O]n an anatomic and physiological basis, there are only a few logical ways to explain the capacity of some supreme suppers:

1. increased stomach size
2. increased gastric emptying speed into the small intestine
3. disappearance of food into the fourth dimension

Click through to read the answer. Hint: It's not #3. (Via KevinMD.)