Nutrition and athletic performance

The ideal diet for an athlete is not very different from the diet recommended for any healthy person.

However, the amount of each food group you need will depend on:

• The type of sport
• The amount of training you do
• The amount of time you spend doing the activity or exercise

People tend to overestimate the amount of calories they burn per workout so it is important to avoid taking in more energy than you expend exercising.

To help you perform better, avoid exercising on an empty stomach. Everyone is different, so you will need to learn:

• How long before exercising is best for you to eat
• How much food is the right amount for you

CARBOHYDRATES

Carbohydrates are needed to provide energy during exercise. Carbohydrates are stored mostly in the muscles and liver.

• Complex carbohydrates are found in foods such as pasta, bagels, whole grain breads, and rice. They provide energy, fiber, vitamins, and minerals. These foods are low in fat.
• Simple sugars, such as soft drinks, jams and jellies, and candy provide a lot of calories, but they do not provide vitamins, minerals, and other nutrients.
• What matters most is the total amount of carbohydrates you eat each day. A little more than half of your calories should come from carbohydrates.

It's beneficial to eat carbohydrates before you exercise if you will be exercising for more than 1 hour. You might have a glass of fruit juice, a cup (245 grams) of yogurt, or an English muffin with jelly. Limit the amount of fat you consume in the hour before an athletic event.

You also need carbohydrates during exercise if you will be doing more than an hour of intense aerobic exercise. You can satisfy this need by having:

• Five to ten ounces (150 to 300 milliliters) of a sports drink every 15 to 20 minutes
• Two to three handfuls of pretzels
• One-half to two-thirds cup (40 to 55 grams) of low-fat granola

After exercise, you need to eat carbohydrates to rebuild the stores of energy in your muscles if you are working out heavily.

• People who exercise or train for more than 90 minutes should eat or drink more carbohydrates, possibly with protein, 2 hours later. Try a sports bar, trail mix with nuts, or yogurt and granola
• For workouts lasting less than 60 minute, water is most often all that is needed.

PROTEIN

Protein is important for muscle growth and to repair body tissues. Protein can also be used by the body for energy, but only after carbohydrate stores have been used up.

But it is also a myth that a high-protein diet will promote muscle growth.

• Only strength training and exercise will change muscle.
• Athletes, even body builders, need only a little bit of extra protein to support muscle growth. Athletes can easily meet this increased need by eating more total calories (eating more food).

Most Americans already eat almost twice as much protein as they need for muscle development. Too much protein in the diet:

• Will be stored as increased body fat
• Can increase the chance for dehydration (not enough fluids in the body)
• Can lead to loss of calcium
• Can put an added burden on the kidneys

Often, people who focus on eating extra protein may not get enough carbohydrates, which are the most important source of energy during exercise.

Amino acid supplements and eating a lot of protein are not recommended.

WATER AND OTHER FLUIDS

Water is the most important, yet overlooked, nutrient for athletes. Water and fluids are essential to keep the body hydrated and at the right temperature. Your body can lose several liters of sweat in an hour of vigorous exercise.

Clear urine is a good sign that you have fully rehydrated. Some ideas for keeping enough fluids in the body include:

• Make sure you drink plenty of fluids with every meal, whether or not you will be exercising.
• Drink about 16 ounces (2 cups) or 480 milliliters of water 2 hours before a workout. It is important to start exercising with enough water in your body.
• Continue to sip water during and after you exercise, about 1/2 to 1 cup (120 to 240 milliliters) of fluid every 15 to 20 minutes. Water is best for the first hour. Switching to an energy drink after the first hour will help you get enough electrolytes.
• Drink even when you no longer feel thirsty.
• Pouring water over your head might feel good, but it will not get fluids into your body.

Offer children water often during sports activities. They do not respond to thirst as well as adults.

Teenagers and adults should replace any body weight lost during exercise with an equal amount of fluids. For every pound (450 grams) you lose while exercising, you should drink 16 to 24 ounces (480 to 720 milliliters) or 3 cups (720 milliliters) of fluid within the next 6 hours.

ACHIEVING DESIRED WEIGHTS FOR COMPETITIVE PURPOSES

Changing your body weight to improve performance must be done safely, or it may do more harm than good. Keeping your body weight too low, losing weight too quickly, or preventing weight gain in an unnatural way can have negative health effects. It is important to set realistic body weight goals.

Young athletes who are trying to lose weight should work with a registered dietitian. Experimenting with diets on your own can lead to poor eating habits with inadequate or excessive intake of certain nutrients.

Speak with a health care professional to discuss a diet that is right for your sport, age, sex, and amount of training.

Exercise - nutrition; Exercise - fluids; Exercise - hydration

Buschmann JL, Buell J. Sports nutrition. In: Miller MD, Thompson SR. eds. DeLee, Drez, & Miller's Orthopaedic Sports Medicine. 5th ed. Philadelphia, PA: Elsevier; 2020:chap 25.

Riley E, Moriarty A. Sports nutrition. In: Madden CC, Putukian M, Eric C. McCarty EC, Craig C. Young CC, eds. Netter's Sports Medicine. 3rd ed. Philadelphia, PA: Elsevier; 2023:chap 5.

Thomas DT, Erdman KA, Burke LM. Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: nutrition and athletic performance. J Acad Nutr Diet. 2016;116(3):501-528. PMID: 26920240 pubmed.ncbi.nlm.nih.gov/26920240/.

Updated by: Linda J. Vorvick, MD, Clinical Professor, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington, Seattle, WA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.