Why Carbs Aren’t Always Necessary for Endurance Events

Happy Monday!!

You might have read the title and immediately were on the defense or you might have read the title and found yourself intrigued. Carbohydrates do get a bad rep, and I am not trying to worsen their reputation. I find that the good, complex carbohydrates are important to our energy systems in the body, among other things, but I also know that it’s not okay to make a blanket statement of “All endurance athletes need carbohydrates for energy and for good performance.” Read more about good and bad carbohydrates here.

While this has been the belief for years, it’s certainly not the case any more. Many studies have shown the benefits of fat adapting and using fat as a fuel source for endurance events, and how it can actually be more beneficial. While I am not going to go into detail about the benefits of fat this week (I am saving this for my discussion on Fats in the following weeks), I am going to present information that details how and why endurance athletes, those competing in marathons, ultras, triathlons, Spartan races, etc, don’t need to consume high carb diets.

With that being said, I also want to indicate that not everyone thrives on low carb, high fat diets either. So in short, a one-size fits all approach to a healthy lifestyle/diet doesn’t work when it comes to food. No one is created the same, thus no one’s nutrition will be calorie for calorie the same. You can live a healthy lifestyle with less carbohydrates and more fats, just as much as you can with high carbohydrates and lower fats. Ultimately, you have to see what works for you and your athletic performance and lifestyle.

I know for me, I need more carbohydrates, but I also have trained my body to fat adapt during my marathon training and for those high intensity workouts and longer miles. I’ve done this by running on empty. This has trained my body to adapt to burning fat as fuel in a more efficient way and faster, thus on race day I reap the benefits. I also incorporate more fat into my body during longer training cycles, trying to eat less simple sugars, the ones that are programmed into distance runners to help provide quick energy.

So let’s dive into how this all works and the science behind it all. I will even include links to some great studies and research done in the recent years to help explain more, and for those who are nerds like myself.

Why does fat adaptation work? 

It’s simple really, science has shown that your body can be trained to use fat as fuel at much higher rates. This wasn’t always the belief. It has always been you need carbs, simple sugars for endurance events, because carbs are easily broken down into energy and at faster rates, thus giving your muscles and body the energy it needs to perform endurance events, such as an ultra marathon or marathon. Those runs and workouts over 1 hour. Carbohydrates have always been the main energy source for fueling our bodies.

Now research has shown us that fat can be converted to fuel, and faster than we once thought. Studies have shown that high fat diets, with low carbohydrates in endurance athletes doesn’t hurt performance compared to high carbohydrate diets, and can even help performance in some cases. This graphic helps to show this correlation.

 

Source

LCD= low carb diet   HCD= High carb diet

*This particular study used 70% fat, 20% protein, 10-12% carbohydrates diet (LCD) vs. 60% carbohydrates, 15% protein & 25% fat diet (HCD). The athletes were the same age in each category with similar height, weight and fat mass. 

Since fat is stored in the body and excess glucose/sugar is stored as fat, your stores are higher and can be utilized as energy. We used to think we had to fuel with sugar to help fill our depleted reserves, i.e. energy chews, gels and drinks during longer duration runs and races. Once those glycogen reserves are depleted, the body taps into fat for fuel. The problem was that it took to long to convert the fat to energy, but now our bodies can fat adapt, using fat just as efficiently as glycogen. Fat adaptation can be helpful for those with gastrointestinal issues, since carbohydrates are the main contributors to GI complaints.

 

source

Low carbohydrate diets with high fat, increase fat oxidation at 59% higher in LCD and at a higher percentage of VO2 Max. Link here to the study.  So, if you can fat adapt, bonking is less likely in the marathon or longer distances, because once glycogen stores are depleted, the body taps into fat and uses it at faster rates. I find this type of training beneficial, in that my body doesn’t have to rely on fueling during my races and I don’t have to worry as much about filling my empty glycogen reserves.

What is also interesting is that what was once thought, less oxygen needed to convert carbohydrates to energy, is not entirely the case. Why is less oxygen helpful?  Because you want all the oxygen you can get to go to your muscles and blood, so you don’t have to work as hard to perform your race or workout. So carbs were thought to use less oxygen, but these studies are showing your VO2 max can be higher with fat adaptation, and less oxygen can be used to burn fat as fuel.

Why Carbs aren't Necessary for Endurance Events #runners #nutrition Share on X

My motive behind this post, is to help shift through some of the confusion, and to bring to light some important research. There’s a lot of myth when it comes to carbohydrates and fats. I also don’t think it’s fair for nutritionists and/or dietitians to say if you are competing in endurance events you need more carbs, because this isn’t entirely true, and blanket statements can’t be made in terms of macro-nutrients percentages. Now you can say that everyone needs all the macro-nutrients, but some will need higher percentages of one compared to another.

I hope you learned some new information and some of your questions were answered. If you have any other questions, leave them in the comment section and I will be happy to answer them to the best of my ability.

Disclaimer: This post is intended for educational purposes only. The statements herein are not intended to cure, diagnose, prevent or prescribe any diet. Please consult a medical professional or nutritionist before beginning a new diet and/or lifestyle. 

Until next Time Be Whole and Be Fit