Changing the Face of Nutrition for Endurance Athletes


As an experienced endurance athlete, I’ve been around long enough to see a shift from our traditional athletic diet to a newer trend in increased healthy fat consumption, while minimizing carbohydrate intake. The traditional endurance athlete diet mainly consisted of a high percentage of carbohydrates, moderately high protein intake and a less of an importance on consuming healthy fats. This goes hand in hand with the idea of “carbo loading” before endurance events. I have been noticing a shift from the traditional endurance fueling to a more high fat, low carbohydrate approach such as a more Paleo, Primal, or on the extreme end, the Ketogenic diet.


The background for the shift is based around studies, such as the FASTER study (Fat Adapted Substrate use in Trained Elite Runners) by Volek, Phinney et al. that have recently shown that a diet high in healthy fats and low in carbohydrates (under 10% of total calories) helps to shift our body from burning mainly carbohydrates as their energy source to fats as the main fuel source to produce energy. This would mean that you could, in theory, get away from slamming energy gels every 15 mins and consume less sugar over the course of your race which can prevent some GI issues that have been known to occur in the later stages of ultra endurance events. Although, this shift to using fat as more of a fuel source is useful in mainly longer events where you are able to keep your heart rate at or below your aerobic threshold. This means that your body is working at a level where your lungs and heart can provide enough oxygen to the working muscles to use your aerobic energy pathways and not shift into using anaerobic pathways to create energy which needs a faster burning fuel source like carbohydrates.
There are other benefits that can be associated with a low carbohydrate diet. One of which is less inflammation throughout the body, which can be caused by the high levels of carbohydrates that a typical endurance athlete will consume. Also, you can get used to packing less food on your long runs and rides which is a bonus because you are consuming less calories over the same amount of time as a typical carb burning athlete. Switching to a high fat, low carb diet also may decrease the risk of you “bonking” on a longer workout, or in a race, because you have a more readily available fuel source, fat, stored in your body. Of course, whether you are burning predominantly carbs or fats in your training comes down to intensity and heart rate. The harder the pace and higher the heart rate, the more your body relies on carbohydrates to maintain energy levels to get through your endurance event.

When it comes to fueling your workouts, a high fat, low carb diet often leaves you wanting in the department of quick, easy workout snacks. I have often made my own high fat workout snacks to help keep my energy levels up during runs and rides. Sometimes it’s as simple as bringing macadamia nuts on my rides or if I have time, I will make almond butter balls or homemade energy bars. More often than not, I simply don’t bring any extra food along because I don’t really notice the low energy situation that I once did while training and racing these long races when I was consuming a carb dominant diet. I have recently begun searching for some pre-packaged bars that contained natural ingredients that had a good ratio of fat to carbs. There are a couple of options on the market and I will keep you guys posted on how they are once I order them up, since of course, I can’t find them in town. One product I have been throwing into my pocket and pack for my long runs over the last little while have been a product called Enduro Bites which have been wonderful, especially in the winter primarily due to the fact that they don’t freeze solid because of the use of coconut oil in their recipe to keep them chewy. Another thing that I’ve been doing is switching my hydration practices to conform to my new diet practices which means ditching the typical high carb drinks in my bottle, in favor of water with some salt or, on my longer runs, mixing in some branch chain amino acids to keep from breaking down too much muscle during these long slogs.


This post is simply just a personal reflection on what I have been doing to fuel my endurance training as well as my healthy lifestyle in general. There is no clear cut nutritional strategy for every person. Some athletes can handle a low carb, high fat diet while training and racing ultra distance events and others need more carbs in order to function and maintain their training load. As always, I’m constantly experimenting and refining my processes. Stay tuned for future blog posts about exercise and endurance sports.

Cam Wilson

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