Exercise burns extra calories and raises your metabolism. So eat every couple of hours -- three meals plus healthy snacks. Before a workout, snack on carbs (juice, fruit, or yogurt) for fast energy. After a long, tough workout, replenish with a carb/protein mix, like a peanut butter sandwich or a smoothie. Otherwise, keep your meals and snacks light: Try an apple and peanut butter, yogurt and nuts, or an egg on whole wheat toast.