Sports Nutrition for Endurance Exercise

Runner opening energy gel packet
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Endurance athletes—which include marathon runners and long distance cyclists and swimmers—have unique sports nutrition requirements. If you exercise at a high intensity for more than two hours per day on most days, the proper diet is essential for optimal performance and recovery.

But what, when, and how much to eat and drink can be confusing for even the most experienced endurance athlete. The following tips provide some general guidelines to help simplify your fueling (and refueling) plan.

How Food Becomes Energy for Exercise

Before developing your plan, it’s helpful to understand how the foods we eat can help fuel your muscles, and also how they can help keep us exercising for hours on end without fatiguing. These foods fall into three general categories: carbohydrates, fats, and protein.


Carbohydrates are the main nutrients that fuel moderate to high-intensity exercise. These foods supply the body the glucose it needs for continued and sustained energy. Eating them enables endurance athletes to keep going without "bonking," in which your blood sugar drops too low and you can't continue.

Yet, research indicates that most non-elite endurance athletes don't consume the necessary amount of carbohydrates to support their hefty training schedule.


Fats can also provide energy, mainly when the exercise is low in intensity and longer in duration. That makes this macronutrient important for supporting training sessions that focus more on endurance than speed.

Monounsaturated fats are the best fats from a health standpoint, in that they help increase the body's HDL or "good" cholesterol, reducing the risk of heart attack or stroke. Adding omega-3 fatty acids reduces inflammation and promotes brain and nervous system function.


Proteins are primarily used to maintain and repair muscle. Though not generally thought about as fuel when endurance training, research shows that these types of foods are needed in slightly higher amounts when engaging in this type of exercise.

Think of protein as providing your muscle the strength it needs to keep pushing through. Proteins also help your muscle recover after a grueling training session or competitive event.

When to Eat Each Food Source

Before getting into the best sources of carbs, fat, and protein for endurance athletes, it's important to know when to consume each of these sources for optimal energy and fuel. This can be broken down by pre- and post-training recommendations, as well as suggestions for refueling during an endurance training or event.


Eating three to four hours before engaging in endurance training or events helps the body start off with a full fuel tank. Often referred to as "loading," the best food sources for this pre-training meal are complex carbohydrates, or carbs that take the body longer to digest.

During the Endurance Training or Event

Glycogen stores have a limited supply and get used up rather quickly—within about 90 minutes to two hours—during high-intensity exercise. If not adequately replenished, fatigue sets in and the athlete needs to slow down or risk "hitting the wall."

That's why it is important to consume carbohydrates throughout long training sessions or endurance events. The best carbs for this purpose are simple carbs, or carbs that the body can digest rather quickly.


After the endurance training session or event, the body needs to refill its energy tank. More carbs can assist with this, but protein is important at this point too, providing your muscles the nutrients needed to adequately recover.

Good Foods for Endurance

Each category of macronutrients (carbs, protein, and fat) includes certain foods that offer higher nutritional value, making them better choices for fueling and refueling the body. Here are a few to consider.


Since pre-training eating involves consuming complex carbs, healthier foods that fall into this category include:

To continue high-level exercise for extended periods of time, athletes benefit from fueling their body during the training session with easily digestible or "fast" carbohydrates. Some good mid-exercise refueling options that won't weigh you down include:


Protein helps the body heal, making it a great after-training food source. Healthier protein food options include:


This category of macronutrients is somewhat tricky, especially since more than 70% of endurance athletes consume more fat than their body needs. However, the body does need some fat to function effectively. Fats that are healthier include:

How Much to Eat

Just as it is important to know what to eat and when, endurance athletes also benefit from understanding how much to eat. This ensures that you obtain the needed nutrients in the right amount without consuming too many calories and potentially gaining weight.

Intake recommendations for endurance athletes are:

  • Pre-training: 6-12 grams of carbohydrates per kilogram of body weight during the 24 hours prior to the training or event, with 1-4 grams per kilogram consumed within four hours of the training or event
  • During a training or competition: 60 grams of carbohydrates per hour if the activity lasts longer than 60 minutes; 60-70 grams of carbohydrates per hour if the activity is longer than 2.5 hours (or up to 90 grams per hour if you can tolerate that much, but this high level is not recommended in hotter environments)
  • Post-training: 1-1.2 grams of carbohydrates per kilogram of body weight during the first 3-5 hours after training or the event, plus 0.3 grams of protein per kilogram of body weight

When calculating your body weight, one kilogram is equal to 2.2 pounds. So, a 150-pound person weighs roughly 68 kilograms (150 divided by 2.2 equals 68).

Although there are no suggestions for consuming fat before, during, or after a training or event, endurance athletes should aim to consume 20% to 35% of their total calorie intake from fat sources.

Hydration for Endurance Exercise

If you exercise intensely for more than three or four hours at a time, you need to be mindful of your hydration needs and drink water before, during, and after you exercise.

Don't rely on thirst to tell you when to drink during exercise. By the time you feel thirsty, you're already dehydrated. It's best to drink small amounts often, rather than gulping a lot at once.

Get into the habit of weighing yourself before and after long training sessions to determine your individual hydration needs and to learn how different weather and training conditions may affect you. You’ll also start to get an idea of how much you need to drink during your regular workouts.

Another simple way to determine your post-workout hydration status is to monitor your urine output and color. A large amount of light-colored, diluted urine most likely means you are well-hydrated. A small amount of dark-colored, highly concentrated urine may mean you are dehydrated and need to drink more water.

The following tips can help you stay on top of your fluid needs while exercising:

  • Before exercise: Drink 7–12 ounces of fluid 15 to 30 minutes before the workout.
  • During exercise: Drink 4–8 ounces every 15 to 20 minutes.

After exercise

Rehydrate by drinking about 24 ounces of water for every kilogram (2.2 pounds) you lost during a workout.

Sodium and Electrolytes

During lengthy endurance trainings and events, you’ll most likely need to increase your intake of electrolytes (sodium, potassium, magnesium) beyond what you get in food alone. This helps support optimal performance, both physically and mentally.

A quick and easy option is to consume an electrolyte-containing sports drink during the training or event. This can help reduce the risk of developing hyponatremia, which is water intoxication caused by below-normal sodium levels.

A Word From Verywell

Every athlete will have their own unique fueling and refueling needs and preferences. By experimenting with different approaches, you will find the approach that works best for you.

Try various foods and food combinations before, during, and after your workouts. Vary the timing of your food intake and the amount you eat as well and, over time, you will be able to determine your optimal refueling style.

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Verywell Fit uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Elizabeth Quinn, MS
Elizabeth Quinn is an exercise physiologist, sports medicine writer, and fitness consultant for corporate wellness and rehabilitation clinics.