The best woman distance swimmer the world has ever seen is lean and serene these days, digging cheerfully just now into her between-workouts morning diet supplement of--yes, cholesterol enthusiasts--hash-brown potatoes. And a fried egg, over easy. And a couple of griddle cakes, each the size of a catcher's mitt. All of which will jiggle around the middle of her breakfast companion, who's having the same. But in the white-hot furnace that drives Janet Evans, it will burn to ash well before her three hours of afternoon tank time are finished and her daily weight-room session begins.
At 24, she has made...