When done correctly, carb loading can provide the ultimate competition experience. But what is carb loading, how is it done, and why? And should you do it? This is what the nutrition expert has to say.

Carb loading, the process of filling up the body’s carbohydrate stores, has been a part of competition preparation for endurance athletes for decades. However, it has been long since carb loading meant consuming loads of bread and heaps of spaghetti for a week or more.

See carb loading facts at the bottom of the article.

Proper carb loading can enhance your competition performance significantly. And it’s neither too late, too complicated, nor particularly risky to effectively carb load for the Marcialonga this Sunday.

But what is carb loading, how is it done, and why? This is what the nutrition expert says.

Kristian Grue, who holds a degree in sports science with a focus on nutrition, is, like most triathletes, exceptionally concerned with nutrition optimization, timing, execution, and details in general. He believes that skiers, specifically long-distance skiers, can benefit significantly from well-executed carb loading.

Also Read: Superfood – Essential Nutrition

What Is Carb Loading?

“Carb loading” is a term used to describe the process of maximizing the glycogen stores in muscles so that they are fully stocked for the start of a competition. The body converts carbohydrates in the diet into glycogen, which can be stored in the muscles.

In a nutshell, “carb loading” involves prioritizing carbohydrate intake over other energy sources for a period to ensure that the glycogen stores in the muscles are entirely topped up. This is often done as part of competition preparation in endurance sports.

Why Carb Load? 

Carbohydrates are converted into glycogen, the primary energy source for moderate to high-intensity exercise. After consuming carbohydrate-rich foods, the body builds up a glycogen reserve in the muscles and the liver. Starting a race with fully topped glycogen stores allows you to maintain intensity and speed for longer.

“You can compare carb loading to driving an electric car. You have a certain range if you start the journey with a fully charged battery. If you start with a partially charged battery, the range at the same performance level will be reduced. You’ll have to reduce your speed to reach your destination,” explains Grue to Langrenn.com.

How to Carb Load? 

Carb loading is actually quite simple, according to Grue:

“Mainly consume carbohydrates, eat well and enough, but avoid overeating.”

“In the past, carb loading used to start a week before the competition. But now we know more about how the body stores glycogen, which is essentially carbohydrates in the muscles. We see now that you don’t actually need more than 22 hours to fill empty glycogen stores,” says Grue, explaining further.

“Muscles have a limited capacity to store glycogen. That capacity can be trained, but regardless, you cannot fill the stores more than full. So 48 hours are more than enough to perform effective carb loading.”

Here’s How to Carb Load 

Grue outlines how a typical carb loading routine for longer endurance competitions can be carried out to ensure that you start with fully topped glycogen stores in your muscles.

Personally, Grue begins carb loading in the last 72 hours before the start.

“I usually start carb loading 72 hours before the competition. That’s when I began to reduce fat and protein as energy sources in favor of carbohydrates. I also cut down on carbohydrate sources with a lot of fiber, and most vegetables and salads are eliminated after this day,” he says.

In the final 48 hours before the start, Grue prioritizes carbohydrates even more.

“The idea is to have increasingly lighter carbohydrates, such as white bread, white rice, and white pasta,” he explains.

For Grue, his main meals during this period might look like this: Breakfast could be oatmeal or slices of bread with toppings like jam, chocolate spread, or brown cheese, but no meat toppings. For lunch, he eats white rice or pasta with a small amount of fish or chicken, but the focus is on carbohydrates, i.e., rice or pasta. Dinner follows a similar pattern.

“Some protein is included, and even bread and rice contain some protein. But for protein sources, I choose the lightest and leanest options possible, avoiding red meat and fatty meat products,” says Grue.

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In the last 24 hours before the start, nutrient intake is almost exclusively about easily digestible carbohydrates: minimal fiber, minimal fat, and protein.

“The last day, I eat only white bread. For lunch, it’s often pasta, and for dinner, maybe a pizza, but with minimal toppings. It’s pizza with tomato sauce and just a light sprinkle of cheese,” says Grue.

Before the race on competition day, Grue often eats oatmeal made from oats he has brought from home. This is partly because he wants to be absolutely sure that he doesn’t consume anything unfamiliar.

“The most important thing is to eat something you’ve had before competitions, something you have experience with,” says Grue.

In the final hour before the start, you can also top up with a sports gel, preferably one containing caffeine.

Are there any common pitfalls or mistakes that athletes often make when carb loading? Yes. Many people think they need to eat a lot. But in the days leading up to competitions, training volume is usually reduced, so your energy requirements are lower than usual.

And no, it is neither too late nor particularly risky to carb load effectively for the Marcialonga this Sunday.

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FACTS: CARB LOADING

• Carb loading is effective for endurance competitions lasting 90 minutes or longer.
• By increasing carbohydrate intake before the competition, the body has more energy available in the form of carbohydrates stored in the muscles.
• Requires adjustments to diet and training volume during the carb-loading period, which typically starts from 72 to 48 hours before the competition. Reduce training volume while increasing carbohydrate intake.
• It is recommended to consume between 10 and 12 grams of carbohydrates per kilogram of body weight per day. For a person weighing 70 kilograms, that’s between 700 to 740 grams of carbohydrates.
• Reduce protein and fat intake to a minimum.

(Source: Data Sport)

Updated January 26, 2024: A version of this article was published in 2023.