Nutrition for Endurance

Reading Time: 6 minutes 35 seconds


Date: 2019-10-02T00:00:00-04:00

Whether you're an endurance athlete or just looking to improve your aerobic exercise, knowing the basic information on nutrients is the first step to improving your endurance training. Learn how to maximize your athletic performance by adjusting your nutrition plan and leave your competition behind.

Endurance and Diet

The most popular endurance events include running, swimming, and cycling. These may be single-activity events such as ultra runs, or multi-sport events such as triathlons. Regardless, any aerobic exercise lasting one hour or more counts as an endurance activity. And you need proper nutrition for endurance whether you take part at an elite or recreational level.

Events vary and so do athletes and your everyday personal training clients. So, it should be no surprise that an endurance diet is not a one size fits all solution. Factors to consider include body weight, environmental conditions, and nutrient timing, just to name a few. Each client will have different needs for different events.

Finding the best solution may involve following recommendations mixed with trial and error. And, as always, keep your scope of practice in mind as a personal trainer—make sure you're cleared to talk about nutrition with clients. Now, let's dig into the details of dietary needs for endurance.


Macronutrients are the basic components of the food we eat. These are carbohydrates, protein, and fat. You must eat macros in proper ratios to fuel your endurance. Healthy adult eating includes ratios of 45-65% of calories from carbs, 20-35% from fat, and 10-35% from protein. Adjust these ratios based on the goal of the physical activity. For example, an endurance athlete would increase the percent of carbs they eat to improve muscle glycogen stores. A strength athlete would consume a higher protein intake to support building more muscle mass.

The Essential Carbohydrate

Carbs come in different forms. The easiest way to think about these are as simple and complex carbs.

Simple carbs, also known as simple sugars, have one to two sugar molecules. These include glucose, dextrose, or fructose; they break down quickly in the body. Foods with simple sugars include fruits, milk, vegetables, table sugar, candy, and soft drinks. They supply energy but lack fiber, vitamins, and other key nutrients.

Complex carbs have three or more sugar molecules. You'll find these in foods like beans, whole grains, whole-wheat pasta, potatoes, corn, and legumes.

So, which kind of carbohydrate should you consume? Most of the carbs you eat should come from complex sources and naturally occurring sugars, rather than processed or refined sugars.

How many carbs should endurance athletes eat? There will be some differences based on the type and duration of training. The general rule is to increase carbohydrate consumption up to 70% of total daily calories to support the high volume of glucose needed for that level of physical activity.

Carbohydrates have 4 calories per gram. Endurance athletes should eat 8 to 10 grams of carbohydrate per kilogram (kg) of body weight per day. This will depend on the duration of their endurance event. For endurance training lasting 4 to 5 hours, endurance athletes should consume 10 grams per kilogram of body weight. For example, endurance runners who weigh 70 kg and complete in an endurance event of 4 hours or more should consume a minimum of 700 grams of carbohydrate daily. In comparison, a power athlete would consume fewer carbs (around 4 to 5 grams per kilogram of body weight). A power athlete's focus will be to increase protein intake.


Many people focus only on carbs for endurance exercise; however, protein intake for endurance athletes is equally important. The purpose of protein is to build and replenish lean muscle tissue. Additionally, protein can act as a source of energy in times of caloric deficits.

There are two different types of protein. Animal-based protein is considered a complete protein. It is complete because it has an adequate part of the nine essential amino acids. Plant-based protein is considered an incomplete protein. This isn't to say it is bad, it just doesn't have all essential amino acids.

Animal-based protein sources:

  • beef

  • fish

  • chicken

  • eggs

  • milk

Plant-based protein sources:

  • almonds

  • oats

  • broccoli

  • chia seeds

  • quinoa

  • hemp seeds

  • peanut butter

How much protein do you need to eat? Protein has 4 calories per gram. Protein intake for a normal healthy adult is around 0.8 grams/kg/day. Endurance athletes should eat protein at 1.4 g/kg/day. Athletes taking part in longer endurance events need more protein than those running shorter distances. For example, endurance athletes weighing 70 kg would need to consume 98 grams of protein daily to support their endurance exercise. Athletes who take part in strength or power sports will consume up to 2.0 g/kg/day.

Endurance athletes on a plant-based diet will have an increased protein requirement due to the plant-based diet consisting of incomplete proteins.


Don't fear the fat! Endurance athletes need healthy fats in their diet. Roughly 30% of your client's daily calories should from fat when they're involved with endurance exercise. Dietary fat has six major roles in the body:

  • Supply energy

  • Help manufacture and balance hormones

  • Form cell membranes

  • Form the brain and nervous system

  • Transport fat-soluble vitamins (A, D, E, and K)

  • Supply two fatty acids the body can't manufacture (linoleic acid and linolenic acid)

There are many types of fat, some good and some not. The most significant types are triglycerides, fatty acids, phospholipids, and cholesterol. Of these, triglycerides are most commonly found in food. Fatty acids break down further into saturated, monounsaturated, and polyunsaturated. Endurance athletes need to minimize the amount of saturated fats consumed. Most of the calories from fat should be in the form of monounsaturated fatty acids.

When trying to add fat to your diet to keep up with the demands of endurance training, focus your fat intake on the following healthy fats:

  • Fatty fish - salmon, mackerel, or tuna

  • Avocado

  • Seeds - sunflower, sesame, and pumpkin seeds all have healthy fats

  • Nuts - peanuts, walnuts, almonds, or cashews

  • Olive oil

  • Eggs

  • Ground flaxseed

  • Beans - kidney, navy, or soybeans

Fluid Intake

We lose water throughout the day through normal respiration, sweating, and urinary output. When we exercise, we lose more. In addition to water loss through sweating, we also lose electrolytes. When we sweat, we also lose sodium, chloride potassium, magnesium, and calcium. These electrolytes serve important roles in supporting bodily systems. There are many electrolyte drinks on the market. However, one of the best ways you can replenish your electrolytes after a long endurance training session is by eating whole foods.

Replenishing Electrolytes with Food

  • Sodium - chocolate milk, bagel with peanut butter, soup

  • Chloride - olives, seaweed, celery

  • Potassium - banana, sweet potato, dried fruits, avocado, kale, peas, beans

  • Calcium - milk, yogurt

  • Magnesium - whole grains, leafy vegetables, nuts, lentils, peanut butter

Endurance athletes need to watch their hydration throughout the day and especially during workouts. As little as a 1-2% reduction in body weight due to water loss can result in decreases in athletic performance.

Fluid Intake Guidelines

The normal daily fluid intake for me is 3.7 liters. For women, it's a little less at 2.7 liters. When your client is taking part in endurance activity, they need to up their intake:

  • 2 hours prior to beginning endurance training: 20 ounces

  • During endurance exercise: 10 ounces every 20 minutes

  • After endurance exercise: 24 ounces for every pound of body weight lost

As if satisfying thirst wasn't enough. Here are the top reasons for proper hydration, which are especially important for clients taking on endurance events:

  • Promotes heat dissipation

  • Improves performance

  • Detoxification at the cellular level

  • Regulation of blood pressure

  • Promotes mental clarity

  • Keeps joints and muscles lubricated

  • Improves digestive process

Nutrient Timing

Having your body ready for peak performance means having nutrients available at the time you need them. Having a nutrient intake plan that includes consumption of carbohydrate, protein, fat, and water is essential to your success. You need to consider consumption before, during, and after endurance training and endurance events.

Prior to endurance training:

  • Consume 1 gram of carbohydrate per kilogram body weight 2 hours prior

  • Consume 20 ounces of water 2 hours prior to the start of endurance training

  • Carbohydrate loading should only occur leading up to an endurance event

During endurance training:

  • Consume 10 ounces of fluid that has electrolytes and a 5% concentration of carbohydrate every 20 minutes

After endurance training:

  • Consume 1.5 grams of carbohydrate per kg body weight within the first 30 minutes post-exercise

  • Consume 15 to 25 grams of protein within the first 30 minutes post-exercise

  • Consume 24 ounces of water for every pound of body weight lost

Nutrition for Endurance: Bringing it All Together

Nutrition for endurance involves a lot. When endurance athletes pay attention to the recommendations and figure out what methods work best for them, the outcome is improved athletic performance. Whether you are an elite athlete, a weekend warrior, or a personal trainer designing programs for athletes, it is important to fuel the body properly. Proper nutrients at the right time allows you to perform at your highest level.

Want to learn more about nutrition and the impact it has on sports performance? Check out the ISSA Nutrition Certification and join a network of experts in sports nutrition.

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