Eat an hour before you exercise. Running on empty doesn’t work — just ask your car! Have a snack that’s roughly two-thirds carbohydrates and one-third equal amounts of protein and fat.
Let the intensity of your workout determine the portion size. “If you’re doing 45 minutes of cardio plus 20 minutes of weights, you’ll expend 500 calories or more,” says Bonci. “A 100-calorie yogurt won’t cut it; aim for 250 to 300 calories.” Pre-workout snacks that fit the profile: a six-inch flour or corn tortilla spread with one tablespoon each of peanut butter and jelly plus a piece of fruit, or half a yogurt smoothie and a packet of instant oatmeal.