All carbohydrates break down into glucose, raising your blood sugar levels faster than any other nutrient. As a result, the pancreas releases insulin to remove surplus sugar from the bloodstream and maintain normal levels.
Research, including a study at the University of Washington School of Medicine, has found that exercise— particularly strength training—increases insulin sensitivity in the muscles. So if you’ve just worked out, more of the carbs you eat afterward will be carried by insulin directly to your muscles for replenishment. (Incidentally, this goes for protein too, which is why it’s helpful to consume a mixture of protein and carbs after training—we’ll discuss this more later.) On the other hand, if you’ve been sitting on the couch watching football, those carbs will just get stored around your waist.
For this reason, we recommend that most of your carbs come before, during, and shortly after training. It also means that you need to eat fewer carbs when you want to get lean—you need to keep insulin levels low. “If someone is in fat loss mode,” says John Meadows, C.S.S.N., a nutrition coach and national-level bodybuilder, “I like to limit carbs to pre-, intra-, and post-workout meals, when they’ll go where you want them”—that is, to muscle tissue. For muscle gain, Meadows prefers to add carbs (shakes included) to meals around training time first, before adding them to other meals. Carb foods include potatoes, sweet potatoes, rice, oats, fruits, and vegetables.
Fruits should be consumed in their whole-food form and limited to two or three pieces daily (excess fructose, the sugar in fruit, is stored as fat). Green vegetables can be eaten steadily regardless of the goal. Eat one gram of carbohydrate per pound of your body weight when dieting and two grams per pound when you want to put on muscle. A fist-size portion of cooked rice or potatoes is about one cup and gives you 40–45 grams of carbs and negligible protein and fat.