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. The key is to only take in the number of additional calories you need while 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
• What type of foods to consume
• How much fluid to comsume

CARBOHYDRATES

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

Keep these factors in mind when choosing carbohydrate-rich foods: 

• Complex carbohydrates are found in foods including starchy vegetables such as corn, legumes, whole-grain breads and pasta, and brown rice. They provide energy, fiber, vitamins, and minerals.
• 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. How many carbohydrates you need depends on the type of exercise you do and how long you do it. Carbohydrate recommendations are:

• Low-intensity exercise (walking, yoga, lifting light weights): 3 to 5 grams per kilogram (g/kg) of body weight
• High-intensity exercise (running, team sports, cycling): 5 to 7 g/kg of body weight
• Endurance exercise for several hours (marathon running, cross country skiing, backpacking): 6 to 10 g/kg of body weight
• Ultra-endurance exercise for 4 hours or more (ultra-marathons, ultra-long-distance cycling): 8 to 12 g/kg of body weight

It's helpful to eat carbohydrates before you exercise if you will be exercising for more than 1 hour. You might have a piece of fruit, a cup (245 grams) of yogurt, or a piece of wheat bread with jam.

You also need carbohydrates during exercise if you will be doing more than 1 hour of intense aerobic exercise. Try bananas, honey, or raisins. Sports bars, gels, and drinks are convenient and can also provide carbohydrates, but don't provide many of the nutrients and fiber whole foods do.

After exercise, you need to eat carbohydrate-rich meals and snacks 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 whole wheat bread with peanut butter or turkey, trail mix with nuts, a sports bar, or yogurt and granola
• For workouts lasting less than 60 minutes, 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.

For athletes, the recommended protein intake is about 1.2 to 2.0 g/kg of body weight per day. Good sources of protein include lean meats, eggs, poultry, fish, beans, nuts and nut butters, and dairy products.

It is a myth that a high-protein diet alone will promote muscle growth. For muscle building, you need strength and resistance training. 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:

• Enough high-quality protein
• A balanced diet that provides the number of daily calories you need

Eating more protein than your body needs does not improve performance or your health. Too much protein in the diet:

• Will be stored as body fat or burned for energy
• 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.

While many people use protein supplements, whole-food protein sources are a healthier option.

FATS

Fats are the main source of energy:

• When you are at rest
• When you exercise at a low to moderate intensity for a long time

You should get 20% to 35% of your calorie needs from fats, depending on the time and intensity of your exercise.

Different dietary fat sources include:

• Saturated fats: Meats, poultry, lard, coconut oil, palm oil, full-fat dairy and dairy products such as cheese, butter, and cream.
• Unsaturated fats: Vegetable oils such as peanut, canola, olive, corn, and soybean, seeds and nuts, fish, and avocado 

Keep these things in mind when choosing foods that supply fats:

• Eat more unsaturated fats (monounsaturated and polyunsaturated fats). You should only get 10% of your total calories from saturated fats.
• Getting less than 20% of your calories from fat can cause a deficiency of essential fatty acids and fat-soluble vitamins.
• Fats take longer to digest, so wait 3 to 4 hours to exercise after eating a full meal. Avoid fried or high-fat foods, which are harder to digest.

MICRONUTRIENTS

Not getting enough of certain vitamins and minerals can affect your performance and overall fitness. Eating a variety of nutrient-rich foods that provide enough daily calories should supply the vitamins and minerals you need.

Important micronutrients for athletes are:

• Iron: Iron deficiency can impair your muscle function and lower your performance. Talk with your health care provider about being tested for iron deficiency if you are a female or you are a vegetarian, a distance runner, or a regular blood donor.
• Calcium: Calcium is important for overall bone health. Not getting enough can lead to weak bones, increased risk for fractures, and blood pressure problems.
• Vitamin D: Vitamin D helps your body absorb and use calcium and phosphorus. It plays a key role in maintaining bone density. It also has anti-inflammatory properties and affects muscle strength and immune system function.

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 20 ounces (2 1/2 cups) or 600 milliliters (mL) of water 1 to 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 to 2 cups (120 to 240 mL) 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 g) you lose while exercising, you should drink 16 to 24 ounces (480 to 720 mL) or 2 to 3 cups 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

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Updated by: Stefania Manetti, RDN, CDCES, RYT200, My Vita Sana LLC - Nourish and heal through food, San Jose, CA. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.