BEFORE: Carbo-loading improves performance for short, intense efforts as well as endurance workouts. But to get the benefit, you should eat at least two hours beforehand—three if it's an especially long effort. For these pre-intensity meals, quickly digestible processed foods like pasta are ideal. "I wouldn't eat salads or bread with the specks of grain in it," says Meyer. "Raw food lingers in the stomach."

DURING: Again, this is a time when processed stuff is your friend. During hard efforts, stick with a variety of gels, bars, and sports drinks instead of sandwiches and the like. They're portable and easily digestible, and the labeling makes it easier to gauge your intake—aim for around 60 grams of carbs an hour (including drinks) for any event lasting longer than 90 minutes. For shorter, intense workouts, lean toward sports drinks, which transport nutrients to the bloodstream faster.

AFTER: Make sure to down a recovery drink immediately after any hard workout to start replenishing fluids, electrolytes, carbs, and protein. Following longer efforts (three-plus hours), plan to eat every hour for the next four—how much depends on what you're doing tomorrow and how big you are. Just don't gorge: "It's better to eat small meals repeatedly," says Meyer. "The whole process of restoring protein, glycogen, and fats is more effective when you stretch the meals out. Try a variation on the traditional Italian diet, which serves up carbs (pasta), followed by proteins (lean meat and fish) and then salad. And don't skip the panna cotta. "Trained athletes are better fat burners," says Meyer. "And you need that fat to store in the muscle for the next day."