When planning meals, you may be tempted to stick to a few familiar sources of carbs. But your system works better when you keep it guessing, so don't let yourself get caught in a rut. Eating a variety of carbs, even some simple sugars, is desirable for athletes, according to the Journal Essentials of Strength Training and Conditioning.

Keep in mind, that's not an invitation to gorge on Froot Loops or candy bars. Foods like potatoes, brown rice, pasta and vegetables should make up the bulk of your carbs. As a rule, you shouldn't eat more than two or three grams of carbs per pound of body weight. Many people overdose on carbs, thinking them "safe" simply because they're low in fat. But your system doesn't discriminate: It stores any excess calories—whether from protein, fat or carbs—as fat.