I jotted down what American swimmer Michael Phelps said when the announcer asked him what he was going to do after winning his first gold medal of the 2008 Beijing Olympics: "Eat, sleep, and swim ... get some calories in."

Good answer. And it must work. Phelps broke all Olympic records for the most gold medals won.

According to one report, Phelps eats about 12,000 calories a day. That's A LOT of calories. The average American eats about 2,000 calories a day and doesn't look near as good in a swimming suit.

What does he eat?

"A lot of pizza and pasta," he told one reporter. "I'm eating a lot of carbs. And sleeping as much as I can."

Top athletes know the best way to come back day after day to win medal after medal is not to let your muscles get fatigued. Adequate rest and a high carbohydrate diet can restore high octane fuel in the form of glycogen to tired muscles. The more glycogen packed into muscles, the better advantage an athlete has to keep going strong in competition.

"Carbohydrate is the main fuel for high intensity exercise," write sports science professor Clyde Williams, Ph.D, and exercise physiology professor David Lamb, Ph,D. "The more demanding the training program or competition, the greater is the amount of dietary carbohydrate needed to replace glycogen stores. Failure to replace muscle glycogen stores will result in the inability to maintain an optimum race pace during endurance competitions."

Fat and protein are important for athletes, too, of course. Along with carbohydrates, fat provides fuel for working muscles. And protein is needed to carry nutrients and oxygen to every part of the body and to build and repair weary muscles.

But don't' try the 12,000-calorie-pizza-and-pasta diet at home, boys and girls. Not unless you are ready to jump in the pool and swim and swim and swim or do other types of intense exercise. To be in good shape, we can eat more calories only if we are willing to BURN more calories in physical activity.

Athletes with rippling muscles have an other advantage than just looking good in Speedos. Muscles are the body's "metabolically active tissue." People with more muscles burn more calories — even when they are sleeping. And because they burn more calories, they can eat more calories ... without becoming fat.

Not a bad mantra. Eat, sleep and swim. It sure seems to pay off.