Eating Right for Running and Racing

The basics of eating for running and racing are similar to the guidelines found at The diet composition for a runner consists of eating mostly carbohydrates, a moderate amount of protein, and limited fat. Eating right for running and racing requires hydrating adequately and consuming sufficient fuel for your muscles.

Hydrate Adequately

The single biggest reason for poor running performance and early fatigue is related to poor hydration. Dehydration impacts running performance when you lose just 2 percent of your body weight in water. Choosing mostly water along with fruits, fruit juices, and dairy drinks throughout the day aids in keeping you well hydrated.

As soon as you are dehydrated, your heart needs to work harder, your body temperature elevates, and you start to feel sick. Under nonathletic conditions, the rule of thumb is to drink eight 8-ounce glasses of fluid per day, which protects most people from becoming dehydrated.

With physical activity, the amount you need to drink increases. Unfortunately, during exercise, the body's thirst mechanism might not be a good guide. Instead of relying totally on thirst, it may be helpful to use your sweat rate and the clock to guide you in consuming adequate fluids.

Calculating Sweat Rate

Your sweat rate will vary by climate conditions. When calculating your sweat rate, run your normal running pace for 1 hour in a variety of temperatures and humidity conditions. Complete the following steps.

  • Step one: Take your weight in the nude before and after a run and note the difference in ounces.

  • Step two: Add to this difference the amount of fluid you drank during the run.

  • Step three: Take this amount and divide by 4 to determine how much you should drink every 15 minutes.


Weight before: 200 pounds
Weight after: 199 pounds
Drank: 8 ounces of water
Sweat loss: 24 ounces/hour

Divide your hourly fluid loss by 4 = 6 ounces every 15 minutes.

If your weight after a run is greater than your weight before the run, you may be drinking too much during the run. Your post-run weight should be the same or within 1 to 2 pounds less than your pre-run weight.


It was once thought that caffeinated beverages dehydrated rather than hydrated the body. Recent studies have shown that caffeine in most popular beverages does not keep the body from absorbing fluid, and caffeinated drinks are acceptable to count as fluid intake. Caffeinated beverages, however, should not be used as the exclusive hydrating beverage.

For runs lasting over 1 hour, it is recommended that your fluid consist of a sports drink that provides carbohydrates, fluids, and sodium. The carbohydrates help prevent your using up your muscle glycogen, the fluid keeps you hydrated, and the sodium keeps your electrolytes in balance. (Electrolytes are chemicals in the body that carry electrical charges necessary for cell function and for using caloric energy.)

Adequate Fuel

When you are running, your body relies on stored carbohydrates and fats to give you energy. Even the leanest runner has sufficient fat stores for running, and yet when you run out of carbohydrate stores, you “hit the wall.” Carbohydrates are stored in your muscles and your liver in the form of glycogen, which breaks down into sugar for use as energy.

Adequate glycogen levels are key to a successful run. Glycogen capacity improves through a combination of a diet adequate in carbohydrates, and through training. Both diet and training optimize the amount of glycogen that the muscles can store.

Viewing, you see that three-quarters of the plate is made up of carbohydrates foods (fruits, vegetables, and grains), which equals about 50 percent of your caloric intake from carbohydrates. Look at your own “plate of food” to evaluate if you have enough carbohydrates. Fruits, starchy vegetables such as beans, peas, potatoes, and corn, along with breads and cereals, are higher in carbohydrate content per serving than non-starchy “green” vegetables.

When evaluating your meal, make sure it is not comprised of exclusively green salad ingredients or you will not be consuming enough carbohydrates.

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