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Should You Carb Load For Endurance Training?

Updated: May 27, 2020

When I was a junior in college, I trained for the LA Marathon. I'm not gonna lie, one of the most exciting parts about training was the concept that I was "supposed" to eat lots of pasta as part of a typical training procedure (I'm not the only one who was excited about this, right?!). During 8 months of training I had ALLLL the pasta, as many people do while training for a marathon or triathlon. I followed carb loading procedures to a T, but I ended up increasing my body's inflammation and risk of hitting the wall (which I most definitely did during my race in the process).

Today I'm going to be talking about carb loading, what it is, why you may want to choose a different option, and what you can do instead!

Why would you want to carb load?

Your muscles can utilize two main sources of energy: muscle glycogen and fat stores. Muscle glycogen is typically what endurance runners or cyclists aim to increase with carb loading. There are a variety of ways you can implement carb loading, but one common method is by eating extremely high carbohydrate meals 1-3 days prior to your long run or race. The goal is to maximize muscle glycogen stores so that you can hopefully have enough energy to get you through the race without bonking/hitting the wall.

Why is it not great?

Carb loading does work for what it's intended to do - fill up your muscles with glycogen. BUT it can be extremely detrimental to your health and race goals. By solely relying on carbohydrates as your source of fuel, your body "forgets" how to tap into its fat stores. Your muscles only store about 2000 calories of glycogen, which you will quickly run through during a long distance race. Once that fuel source runs out, your body isn't able to tap into it's fat sources because it has only been relying on glycogen and isn't accustomed to breaking down fat - cue immediate drop in energy and glucose shut off from the brain... you're officially hitting the wall.

What about gu/energy gel packs?

Traditionally, in order to continue relying on carbohydrates as fuel even as you approach hitting the wall, many athletes will use gu or gel energy packs. These purely contain simple sugars that provide immediate energy to your muscles. Speaking from experience on using these, it's a hassle to eat while you're running AND you're flooding your system with simple sugars that increase the dangerous AGEs in your body and significantly raise your risk of injury and long term inflammation.

And wouldn't it be nice to not have to buy and hold packets of energy when you can tap into your own portable source instead? Something that WON'T increase inflammation, shut energy off from the brain, or cause you to hit the wall?

What should you do instead?

Every athlete knows the importance of cross training. When it comes to your diet, it's crucial to include "cross training" as well. This means training your body to be able to easily switch back and forth between fat burning and carb burning so that when carbs run out, you can effortlessly switch to fat burning! This concept is called Metabolic Flexibility and has been a game changer for my own training goals as well as those of my clients who are professional athletes. You can easily achieve Metabolic Flexibility by utilizing Intermittent Fasting, proper nutrient timing, and Crescendo Fasting. With this combination, you'll reap the benefits of Metabolic Flexibility by not hitting the wall, decreasing your recovery time, decreasing inflammation that occurs from long distance training (bye-bye sore joints!), and saving money on NOT buying energy gu packets! As with any type of training, it may take a few days to a few weeks to adjust, depending on how dependent your body is on carbohydrates as a fuel source. But once your body can efficiently switch back and forth between the two fuel sources, your endurance, recovery, and PRs will all greatly improve! AND you'll feel GOOD!

As an athlete myself, I'm always looking for ways to better my performance while minimizing damage that occurs from the stressors of working out. Metabolic Flexibility is key for endurance athletes to achieve both of those factors.

You can find out exactly how to become Metabolically Flexible with IF, proper nutrient timing, and Crescendo Fasting with The Ultimate 21 Day Intermittent Fasting Program! It reviews the science, the how, the why, and the what of Intermittent Fasting. It also has a section dedicated to tailoring the Program to increasing your lean muscle! Find out how to get started HERE!

Your Nutritionist,


Autumn Elle Nutrition

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