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Nutrition 101: Proper Fueling for Endurance Events

Proper fueling is essential for achieving peak performance. Without it, no amount of fitness or training will help. With that said, there are some basic guidelines that one can follow. It is important to note that nutrition is a very individualistic thing; what works for one may not always work for another. Each person must test out and find what works for them. A base guideline for nutrition while exercising is as follows:

Each of these ranges depends on any number of factors such as bodyweight, outdoor temperature, course profile, perceived expenditure, weather, etc. The key is to take in as much fuel as needed but no more. If you take in more than is needed it will lead to issues such as stomach distress, gastrointestinal issues, hyponatremia, hypernatremia, etc. Most people cannot absorb more than the above recommended amounts.


Calorie expenditure is considerably more during exercise than calories consumed. With that said, rather than trying to replace calories burned with calories consumed an athlete would fill the deficit with energy from body fat. This is commonly known as metabolic efficiency. Almost every person has more than enough excess body fat to accommodate any excess calorie expenditure. One pound of fat equals about 3,500 calories. If an athlete is burning 600 calories per hour and consuming 300 calories of carbohydrates, then one pound of fat, in theory, would last them 11.5 hours.

Still, one cannot burn just fat alone. To unlock the utilization of fat stores one must burn glycogen stores in the liver also. The key to this is eating the right ratios of carbohydrates during exercise in order to burn fat. Think of it as if you are trying to start a fire. You cannot just lite a log on fire. You must start with kindling and small pieces or lighter fluid. Then once that is lit then you gradually add bigger pieces until the fire is going. It is only then that you can start burning big logs that hold the most density and burn the longest.

The ratios in which you burn carbs to fat also depend on the intensity of exercise. The harder you go the more carbohydrates you burn. The slower you go the more fat you burn. Either way you burn both carbs and fat, just in different ratios. Think of the fire scenario again. If I burn a lot of small kindling it burns really hot and really fast, but then it dies. If I burn a big log, it burns really slow for a long time. Same with your body.

While there have been many articles and studies supporting different theories, personally, I have found that consuming calories rich in carbohydrates during exercise have worked best. Taking in sugar through vehicles such as gels work well for me in shorter events (15 hours and below). The longer the event then the more complex carbohydrates (and savory foods) I will add in to help with caloric intake and palate fatigue. Some studies show that taking in a moderate amount of protein in longer events benefit the athlete also. In longer events, such as multiday events, athletes may find that they need real food or crave foods that have more fat, protein, and salt in them.


When consuming fluids there are several things to consider. Some of these considerations are duration of the event, pallet fatigue, electrolyte intake, etc. Below are a few options to consider when hydrating for your event:

You may find that one of these hydration options (or even a mixture) work best for you. This may vary from event to event, environment, needs, etc. Trial and error while learning your body is the best way to know.

Sodium Chloride (Salt)

It is important to take in the proper amount of electrolytes to achieve desired performance and prevent issues such as cramps, hyponatremia, and hypernatremia. Often athletes tend to over hydrate and not take in enough electrolytes rather than becoming dehydrated. Below are a few options to consider when hydrating for events:

When fueling for exercise knowing your body and trying out different fueling options and amounts will serve you best in the long run. These options and amounts may vary with each workout session or endurance event, so having proper knowledge of how and when to implement each is key.

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