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Endurance Athletes Nutrition Misconceptions | JM Nutrition

Endurance Athletes Nutrition Misconceptions | JM Nutrition

Endurance Athletes Nutrition Misconceptions No One Told You About

By: Johnny Zhao, MHSc, BASc, RD, Sports Nutrition Dietitian, edited by the JM Nutrition team

Nutrition for endurance athletes is a topic that is becoming increasingly more popular, at least in the fitness and sports nutrition realm. Because there’s a great deal of information on the topic online it is critically important to distinguish between endurance sports nutrition fact and fiction. As a result, our sports dietitian who specializes in the area, took it upon himself to compile a list of common endurance athletes nutrition misconceptions that no one ever told you about. 

Let’s take a closer look at these.


Endurance Athletes Nutrition Misconceptions


1. Eating more will help you perform better

This is a frequent sports nutrition misconception.

Many athletes commonly consume large amounts of food in an attempt to improve their performance leading up to an event. For example, on the day of the competition, some athletes may consume multiple energy bars to get an edge on the competition. 

Doing so may be problematic. Reason being, these individuals may soon find themselves with abdominal pain, cramping and other undesirable side effects.

Why does this happen? 

When we exercise, most of our blood is directed towards the muscles and not the digestive system (de Oliveira et al., 2014). This means we must be very selective about the types of food we eat before and during a race to prevent negative effects on our performance. If your body is not used to having certain foods, you may experience symptoms of poor digestion.

This can be caused by a variety of factors, but an often theorized one is the lack of fluids with increased carb (and fibre) intake. If you don’t want to end up like Michael Scott on the Fun Run, you should probably take a more structured approach, when it comes to food intake during a race.

There are also multiple endurance sports nutrition studies that show the rate of carbohydrate metabolism does not change regardless of how much is consumed before exercise (Rothschild et al., 2020). However, having a source of carbs beforehand still shows increased performance compared to exercising fasted.

It is, therefore, important to have a plan for what type and how much nutrition to have throughout an endurance competition. We will broach the subject in the sections that follow, so read on.


2. Fast absorbing carbs are better than slow absorbing carbs during exercise

Undoubtedly, this is a firmly held belief by some athletes. However, this is an endurance nutrition misconception. And here’s why.

Although this statement may seem true, it is too simplistic to classify carbohydrates as either “fast” or “slow” absorbing. This is a significant point to which all athletes, including endurance athletes, should pay heed.

Even the fastest absorbing carbohydrates are only used by the body at around 60g (or 240 Calories) per hour (Jeukendrup, 2014). This is a far stretch from how much energy is being used from intense exercise, which can be up to 1000 Calories or more.

Due to this fact, it is crucial to take into consideration whether a food source contains single or multiple transportable carbohydrates. By itself, a single type of sugar is limited in how much energy it can give during exercise. In combination, however, this is drastically increased. Again, this is an important point to underscore.

In a study that examined the effects of consuming a glucose-only drink versus a glucose and fructose drink, the latter increased the oxidation of carbs in the body by up to 75% (Currell & Jeukendrup, 2008).

Consequently, for training and competition under a few hours long, single transportable carbs may be sufficient. This is because you are using primarily internal carbohydrate, or glycogen stores in the body.

If, on the other hand, you’re an endurance athlete preparing for an event that spans several hours, then you would want to consider incorporating multiple transportable carbs to your competition nutrition. This is often a combination of glucose, fructose, maltodextrin and other sugars.


3. It doesn’t matter how I get my nutrition if hit my macros

Frequently, many endurance athletes believe that as long as they get enough food throughout the race, it doesn’t really matter how they consume it.

Unfortunately, however, this endurance diet belief couldn’t be further from the truth.

Although solid and fluid sources may be similar in macronutrient composition, they are digested differently. This is important to understand.

In theory, solid foods will always require additional processing in the stomach to digest when compared with fluids.

In sports such as cycling, where your centre mass remains constant, it will certainly be less of an issue.

If, however, a large amount of solid food is accompanied by an activity such as long-distance running, where your centre mass is constantly shifting, it can cause abdominal pain, bloating and nausea.

You may certainly feel that you can “power through” or “tough out” this type of pain. However, while you’re doing that, the other competitors will likely breeze past you on the course.

Tip for cyclists:

What should you eat as a cyclist?

You can try an energy bar or homemade rice cake with water may be good intra-competition snacks. This especially applies to extended races.

Tip for marathon runner and triathletes:

Marathon runners and triathletes, on the other hand, should take a different course of action with their endurance diet plan.

We recommend primarily liquid sources of nutrition. Examples of this include sports drink mixes or energy gels consumed with water. Not only will these be better tolerated in the stomach, but they are formulated for optimal carb uptake by the body.


4. I should avoid fats because they don’t help with performance

If you consume a high amount of fat shortly before exercising, you may feel digestive distress. Reason being, fat is absorbed slower than other macronutrients.

That said, fats are essential for performance for all types of endurance athletes. For any endurance competition, the primary pathway for energy production is aerobic glycolysis. This means that for the large part of the race, you will be using free fatty acids for energy.

What’s more, the amount of dietary fats you need varies based on whether you’re a trained or untrained athlete.

If you are an experienced endurance athlete, it is possible you are using more fats and fewer carbs for energy. Therefore, for athletes that have trained for years but have not adjusted their nutrition, their performance ends up plateauing. In order to overcome this, the endurance athlete’s diet must be adjusted to account for physiological changes to their bodies. This is just another reason why the endurance diet must be personalized.

To incorporate more healthy fats in the diet eat nuts as snacks throughout the day. You can also add seeds to smoothies and salads. Similarly, choose fatty fish as a protein source at lunch or dinner. 


5. This nutrition plan works for so-and-so, so it must work for me

It’s tempting to simply duplicate the nutrition plan of a high-level athlete, friend or family member. After all, it’s quick and easy. And, it worked for them, so why shouldn’t it work for me?

Unfortunately, things are not so simple.

Reason being, everyone’s body and metabolism are different. As such, we need to account for this, when creating an endurance diet plan.

An example of this occurrence would be when an intermediate level cyclist follows the nutrition plan of Lance Armstrong. Lance may be eating more than 100g of carbs, mostly in the solid form, and drinking more than one litre of water per hour.

When the intermediate cyclist does this, they may find themselves bloated, lethargic and in need of the bathroom. This happens because athletes metabolize foods at different rates depending on their size, genetics, and degree of fitness. They also do not have the benefits of EPO, which maybe (just maybe) helped with his performance.

Furthermore, for most athletes, the recommended carb intake for an athlete would not exceed 90g per hour. Most of the time, it is much lower. This depends on the duration of the training or competition.

Moreover, fluid nutrition sources are also preferred since they are better tolerated through exercise. As for water intake, it depends on your sweat rate, the temperature and humidity.

In general, there is a great deal of trial and error involved. One thing is certain: you should tailor the sports nutrition plan based on what works for your body, not someone else’s.


6. I need to constantly be drinking water

Surely, this is another relatively common endurance nutrition misconception.

This may seem counterintuitive, but drinking more water may not always be better. If rehydrating incorrectly, it may even be dangerous.

Here’s how.

During endurance sports, it is normal to sweat at least 1-2 litres per hour. This is mainly to cool our body down from heat production through our metabolism.

Water loss, however, is accompanied by electrolyte losses which include sodium, potassium and chloride. When these levels get too low in the body, it could lead to nausea, loss of consciousness or even death.

That is precisely why for extended training and races, it is important to have a sports drink or electrolyte mix with the water you’re consuming.

How much fluid should I ingest during an endurance race?

Before entering a competition, it may be a good idea to estimate your sweat rate to determine how much fluid you should drink during a race.

To do this, you can use this equation:

(pre-exercise body weight – post-exercise body weight + fluid intake – urine volume)/exercise time in hours.

In addition, if you’re competing in hot climates, drinking cold water helps to mediate your core body temperature and prevent heat related problems.

Related: Why is Water Important and Much Water Should You Drink


7. It’s better to train fasted to improve body composition

Although there is research for carbohydrate periodization and “training low,” this is often done unintentionally or with the goal of losing body fat.

This, however, may work against the athlete’s goal. As such, we feel this to be one of those endurance sports nutrition misconceptions.

Reason being, endurance training is highly catabolic and may result in a loss of muscle, if not accompanied by proper nutrition.

In prolonged exercise, glycogen stores are depleted, and carbohydrates are not as readily available. Our bodies then have increased oxidation of amino acids for energy (Tarnopolsky, 2004). If no protein is consumed, the only way for our bodies to get this is from our own muscles. Not only does this negatively impact recovery, but it could also reduce overall performance.

That is why it may be beneficial to consume not only carbohydrates, but also a small amount of protein, before and during exercise.

Additionally, for intra-workout nutrition, having branched chain amino acids (also known as BCAAs) may help to prevent muscle breakdown. This contains leucine, which is the main amino acid responsible for activating muscle protein synthesis. As for training low, it should be periodized with the appropriate type of training to ensure it is beneficial for performance and body composition.


We hope that this overview of endurance athletes nutrition misconceptions has provided some insight. We also hope that some of the tips and strategies we supplied will be of practical help to various endurance athletes. As always, the best course of action is to do some trial-and-error to see what works for you. After all, we are all made differently. 

And, if you require, diet optimization for endurance sports or help with personalized meal planning, feel free to contact us for a free consultation.



Currell, K., & Jeukendrup, A. E. (2008). Superior endurance performance with ingestion of multiple transportable carbohydrates. Medicine and science in sports and exercise, 40(2), 275–281. https://doi.org/10.1249/mss.0b013e31815adf19

Jeukendrup A. (2014). A step towards personalized sports nutrition: carbohydrate intake during exercise. Sports medicine (Auckland, N.Z.), 44 Suppl 1(Suppl 1), S25–S33. https://doi.org/10.1007/s40279-014-0148-z

de Oliveira, E. P., Burini, R. C., & Jeukendrup, A. (2014). Gastrointestinal complaints during exercise: prevalence, etiology, and nutritional recommendations. Sports medicine (Auckland, N.Z.), 44 Suppl 1(Suppl 1), S79–S85. https://doi.org/10.1007/s40279-014-0153-2 

Rothschild, J. A., Kilding, A. E., & Plews, D. J. (2020). What Should I Eat before Exercise? Pre-Exercise Nutrition and the Response to Endurance Exercise: Current Prospective and Future Directions. Nutrients, 12(11), 3473. https://doi.org/10.3390/nu12113473

Tarnopolsky M. (2004). Protein requirements for endurance athletes. Nutrition (Burbank, Los Angeles County, Calif.), 20(7-8), 662–668. https://doi.org/10.1016/j.nut.2004.04.008


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Johnny Zhao is a sports dietitian who specializes in nutritional support for endurance athletes and combat sports nutrition. Contact us to book an appointment with Johnny.