You need energy to exercise and energy comes from food. Make sure you've eaten adequately before any fitness activity and eat to refuel afterwards, says Sue Travis, RD, PhD, of the division of nutritional sciences at Cornell University in Ithaca, N.Y.
The amount of food a person needs will varies with age, sex, weight, and activity level. The rate at which you burn calories depends not only on the type of exercise you do, but also on how vigorously you do it.
Travis emphasizes that it’s important to divide your calories between carbohydrates, protein, and fat:
- Carbohydrates. Carbohydrates — sugars and starches — are broken down by the body into glucose, which muscles use for energy. Excess carbs are stored in the liver and tissues as glycogen and released as needed. It’s glycogen that provides the energy for high-intensity exercise and prolonged endurance. Some good sources of carbohydrates are whole grain breads and cereals, fruit, vegetables, pasta, and rice.
- Protein. Protein should be part of each of your major meals because it will help slow absorption of carbohydrates. Fish, eggs, chicken, meat, and beans are excellent sources of protein, and 3 ounces per meal is enough.
- Fat. You need some fat in your diet, too, says Travis. Low-fat dairy products, like 1 percent milk, and lean cuts of meat will give you the fat your body needs.
Try to have a combination of items from all three of these food groups at each of your major meals, says Travis. For a healthy breakfast, have a high-fiber cereal (either oatmeal or another whole-grain cereal), a low-fat dairy product, and fruit or a glass of juice. The easiest lunch might be a sandwich made with lean meat, poultry, or fish on whole-grain bread, with raw veggies and fruit served on the side. Protein and energy bars can be useful, but don't use them as a meal replacement, warns Travis. Look for bars with at least 10 grams of protein and some carbohydrates, rather than products with a high protein content and hardly any carbohydrates.