Written by Fit with Food Dietitian Grace Duffy, RD, LDN

Why is nutrition important for distance running?

Distance running, or endurance exercise, requires extra nutrition attention given the high demand that it places on the body. In order to use fuel efficiently, your body relies on carbohydrates as the primary fuel for endurance activities. The body can store carbohydrates as glycogen, which is found in your muscles and the liver. As you run, the liver breaks down glycogen stores. However, after a certain point, the glucose released by the liver can no longer keep up with your blood sugar needs. As a result, the amount of glucose in your bloodstream becomes limited. Therefore, adequate intake of carbohydrates prior to a run (and sometimes during a run, depending on length) is important to maintain energy and prevent low blood sugar.

Protein is another important component of daily nutrition for running. Endurance athletes have higher protein needs than the average person, with protein needs for athletes ranging from 1.2 to 2 grams per kilogram of body weight. Protein is essential to help maintain muscle stores and plays a role in the rebuild and repair of muscle after activity. It is best to spread protein intake out throughout the day rather than consuming the majority in one meal.

Finally, adequate energy balance throughout the day is of the utmost importance. The longer our bodies spend in an energy deficit during the day, the more likely it is that stress hormones (specifically cortisol) will increase. It is important to spread out calories and protein throughout the day and focusing on re-fueling within an hour of a workout or run. Runners should be consuming at least 3 meals per day, with additional snacks as needed.

Adequate energy balance

Each athlete has different requirements for how many calories they need during the day. Daily energy expenditure depends on age, sex, height, weight, level of activity during the day (e.g. desk job/sitting most of the day versus physical work for occupation), and level of physical activity or exercise (e.g. running, strength training, etc.). As mentioned above, you gain the most benefit from eating balanced meals with adequate carbohydrates, protein, and color (fruits/vegetables) throughout the day rather than having light meals and eating your heaviest meal in the evening. 

Carbohydrates can be classified as simple or complex carbohydrates. Simple carbohydrates are made up of one or two glucose molecules and are generally quick-acting and easy to digest. These carbohydrates have a role for fuel prior to or during a run as they will be able to be used quickly for energy. Examples include juice, candy, cookies, or white crackers. On the other hand, endurance athletes want to include sources of complex carbohydrates during meals as these carbs have additional fiber and nutrients. Examples of these include whole grain products (bread, pasta), fruit (especially with a peel), and starchy vegetables such as corn or potatoes. These complex carbs help you to stay fuller for longer and provide long, sustained energy throughout the day.

With regards to protein, aim to eat at least 15-20 grams of protein at a meal. Americans tend to eat more protein as the day progresses; however consistently consuming protein during the day can be of the greatest benefit for your muscles. Examples of a protein-rich breakfast include overnight oats with protein powder, Greek yogurt with fruit and granola, cottage cheese with fruit, or an egg omelette with vegetables. Consuming some protein soon thereafter a workout will also help athletes to start the process of rebuilding and remodeling muscle. 

Given that endurance athletes utilize mostly carbohydrates during activity (and the higher the intensity, the more carbohydrates an athlete uses), these are the main nutrients to adjust on a day to day basis. Utilizing the athlete’s plate can help to scale your carbohydrate intake up or down, depending on your training load. A light training day (e.g. little activity or a rest day) plate would consist of 50% fruits and vegetables, 25% carbohydrates, and 25% protein. A moderate training day includes more carbohydrates with less reliance on color. A hard training day has the greatest amount of carbohydrates – with 50% of the plate being carbohydrates, 25% protein, and 25% fruits and vegetables. Utilizing these plates can help you to adjust your carbohydrate intake depending on your daily training volume! 

Prior to a run

While many people can “be fine” without eating prior to a run, it is recommended to eat carbohydrate-rich foods prior to endurance exercise! As mentioned above, your body’s primary fuel source for running is carbohydrates. Eating simple carbohydrates prior to a run will help to keep your blood sugar stable and provide the energy that you need before a run. The longer you are running for, the more carbohydrates you need to eat. Timing for a carbohydrate snack or meal should generally be within 60 minutes before you run. However, if you are running for more than 60 minutes, you will need to eat more carbohydrates to support this long run and therefore need to eat earlier to give your body some time to digest your fuel. Each person is different with how far in advance they need to eat to ensure a happy tummy while running – test out what works for you!

Aim for easy-to-digest carbohydrates that are low in fiber. Low fiber fruits are a common pre-run snack, including bananas, applesauce, dates, dried mango, or diced fruit cups. Some people prefer a crunch, so you could try low fiber cereal, a granola bar, pretzels, or animal crackers. Looking for something sweet? Try out candy, an energy gel, or fig bars. Finally, if you struggle with nausea prior to a run (this can be a common issue for morning runners), liquids that contain carbohydrates (e.g. sports drinks) can also work before a run. 

During a run

As mentioned above, after about an hour of running, your body struggles to maintain your blood glucose with the breakdown of glycogen from the liver alone. In order to prevent low blood sugar and to provide energy during a run greater than 60-75 minutes, you need to consume easy-to-digest carbohydrates during a longer run. Recommendations for “how much” depend on your length of run – for activity lasting 1 to 2.5 hours, aim for 30-60 grams of carbohydrates an hour. For a run lasting greater than 2.5 hours, the recommendation increases to 60-90 grams/hour of carbohydrates. A general starting point would be to aim for a sports gel every 30-45 minutes. Everyone is different for how much they need and can tolerate at a time- find what works for you!

Given that there is such a wide variety of sports nutrition products with varying amounts of carbohydrates, practice your fueling plan during your long runs. The more you can replicate training runs to be close to your race day fueling plan, the easier it will be. Additionally, having the knowledge of what works for your stomach prior to those race day nerves can ease some of the anxiety around fueling during a half or full marathon.

Just as we do not want heavy foods on our stomach prior to a run, we also want to aim for easy-to-digest and simple carbohydrates during the run. Many people like to fuel with a mix of sports gels or chews and/or sports drinks. Sports gels are manufactured with different types of sugars, therefore increasing the amount that your body can absorb at one time. Gels tend to be easy to digest and easy to consume. Brands vary with the amount of carbohydrates, presence of caffeine, and amount of salt or electrolytes. Common brands that many runners enjoy include Huma, Maurten, Gu, SiS, Hammer, UCan, HoneyStinger, or Cliff Bloks. Find what gels or chews that you like, fit your desired price point, and that your stomach can tolerate.

Hydration

Hydration is also important to consider during a run, especially with the warmer summer months upcoming. The body is composed of 60% water, and a decrease of 2% body weight from dehydration can cause adverse effects. Dehydration affects your body’s ability to remove heat, which causes you to use more glycogen and decreases stomach emptying. Being dehydrated can sometimes lead to nausea due to the slow emptying of the stomach. Given these adverse effects from dehydration, it is important to stay hydrated prior to and during a run. The more you sweat, the more fluid you are losing! It is important to replace these fluid and electrolyte losses after a run to maintain optimal hydration.

Everyone is different with how much they sweat during an exercise session (sweat rate). It can be helpful to know how much sweat you generally produce so that you can understand your hydration plan. Do you get back from a run and your clothes are sopping wet from how much you have been sweating? Or are your clothes just damp? Sweat rate does change based on the weather conditions. Understandably, one will lose much more fluid on a hot, summer day in comparison to a winter day. 

If you are curious how much fluid you lose during a run, you can try out this simple exercise. First, after eating/drinking breakfast, weigh yourself naked prior to a training run. If you are drinking anything during a run, keep note of the amount consumed. Once you are finished with your run, remove clothes and take your post-run weight. Subtract your post-run weight from your pre-run weight. For every pound of body weight you lose, you have lost about 16 ounces of sweat/fluid. For example, a runner weighs 155 lbs prior to a run. She takes her weight after a run, which is 152 lbs. 155 – 152 = 3 lbs → 3 lbs x 16 oz = at least 48 ounces lost from sweat! If an athlete consumed any fluid during the workout, you would add that after the pre minus post run calculation (e.g. if she consumed 10 oz during the workout → 48 + 10 = 58 oz total lost). This number can be used to better guide how much fluid you may need to take in on an hourly basis and/or how much fluid you need to drink after a run to replace fluid losses.

While sweat rates vary in different weather conditions, your individual sweat composition stays the same (no matter how much you sweat). That being said, when comparing from person to person, each athlete has a different sweat composition in regards to sweat concentration. You lose electrolytes in sweat, primarily sodium (but also potassium, magnesium, and calcium). If you notice salt crystals on your skin or white lines on your clothing/hats, you likely are a salty sweater. This means that you have a greater need to replace sodium after a run! Others may not lose as much salt in their sweat, therefore needing to replace less sodium after a run. Sweat composition from person to person varies greatly, so work with a sports dietitian to determine how much sodium you may need to replace after a run.

Quick checklist for nutrition basics for long distance runners

• Am I eating at least 3 meals a day with protein?
• Am I eating a carbohydrate-rich snack sometime before I run?
• If I am running for >1 hour, am I bringing some type of fuel/gels?
• Am I eating a carbohydrate/protein snack or meal within an hour of finishing a run?
• Am I staying hydrated during the day and replacing fluid losses after a run?

If you answered no to any of the above and need more individualized help, reach out to us for a nutrition running consultation!