What do Olympic gymnasts eat?..... With rock-hard biceps and abs that would make a bodybuilder jealous, Stephen McCain doesn’t need to lose weight. Yet count him as a devotee of the increasingly popular low-carbohydrate diet. A 2000 U.S. Olympian trying to make it back to the Games this year, McCain started doing the high-protein, low-carb thing well before it became the biggest diet fad in the country. “I used to think it was all about carbs, carbs, carbs to get the energy,” he said.