Using a simple, well-balanced diet formula, you can figure out what to eat and when so you have the energy you need to exercise.

By Barbara Robb

Medically Reviewed by Pat F. Bass III, MD, MPH

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.

Fitness Food: The Right Diet for Exercise

The amount of food a person needs will vary 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 — 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 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.

Fitness Food: Timing Meals and Snacks

If you exercise in the morning and don’t have something to eat first, you can use up all of your stored energy. If you’d rather not have breakfast before you exercise, try eating a small piece of fruit.

If you’re planning a strenuous workout, eat a meal high in carbohydrates at least three to four hours beforehand. Choose foods that are easily digested. Travis suggests that you experiment with different foods to see what gives you the most energy.

Fitness Food: Factor in Fluids

It’s particularly important to drink fluids before, during, and after exercising. If you exercise strenuously, try to drink fluids even if you’re not thirsty.

Water is a good choice for most activities. If you exercise continuously for 90 minutes or more, you might benefit from a sports drink that contains electrolytes and carbohydrates. But sports drinks are designed for people who are doing endurance activities for prolonged periods. They probably aren’t necessary for the average person.

Caffeine is dehydrating. Travis suggests that you drink an equal volume of water if you drink coffee or another caffeinated beverage.

The bottom line on fueling for exercise is if you drink plenty of fluids and eat regular meals that include carbohydrates, protein, and fat; you should have all the energy you need for your workout plan.