Is Carb Loading Before A Big Race A Good Idea?

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Carb loading is important for marathoners to do two weeks leading up to their race while tapering. Is Carb Loading Before A Big Race A Good Idea?

One of the many perks of running is we often get to indulge in our favorite foods. This means pizza, burger and beer post half or full marathon. But when we think about pre-race nutrition, many foodies can’t wait to sink their teeth into a large bowl of spaghetti and let taste buds explode in happiness with every bite of saucy pasta dishes. But is carb loading even a good idea before that big race?

Here’s the skinny on carb loading.

What Is Carb Loading?

Carb loading is the nutrition strategy used by runners and other endurance athletes to be able to increase the number of carbohydrates stored in the body before a big race or event. The idea is that carbs are stored as fuel for the body to be able to withstand performing during a long race like a marathon.

Runners have probably heard about eating that big pasta dinner the night before the race. Some runners do not exercise for a day and consume a high-carb diet for one day, but proper carb loading (to feel real results in performance) is not just done the night before or with just one meal.

“One of the misconceptions around carb loading is that you just need to eat that big pasta dinner before,” Jen Rawson, R.D told RunnerClick. “But in fact, it’s more about eating consistently a higher carbohydrate meal pattern leading up to the race.”

Photo by Eiliv Aceron on Unsplash.

In fact, many runners prefer to eat a more filling lunch and go light on dinner the night before the race to make sure there are no stomach issues.

Rawson revealed this means runners eating 45 to 65 percent of their calories from carbs. Runners should also start carb loading two weeks leading up to the race day while tapering. “It’s more about eating a high carb diet in the weeks leading up to a race and decreasing your activity.

Why Runners Need Carbs

Carbohydrates are the body’s preferred source of fuel.

Carb loading allows the body to builds up its glycogen stores, which basically is glucose that is stored in the cells of the liver.

“On average most people can hold about 90-minutes worth of glycogen. So carbohydrate loading is to maximize that storage to get that full 90-minutes out of it as much as we possibly can,” Rawson said.

Photo by Andrew Tanglao on Unsplash.

Carbs have this negative connotation around them where people think they are “bad” or they make us fat. This is not the case. Rawson said that they play a pivotal role in our body, and contain many nutrients like fiber and B-vitamins. Carbs aren’t just sugar—well when eating the “right” carbs like brown rice and whole grains and not donuts.

At its core, carbs do break down to glucose, but that is needed to run the body and the brain. We simply wouldn’t function without it.

“We shouldn’t be fearful of them,” she said. “My suggestion is to try a high carb day and then go for a run and notice how you feel in terms of your energy level.”

Is It A Good Idea To Carb Load?

There are many who do the opposite and following a strict no carb diet like the keto diet. But kept can actually hurt performance for runners. That doesn’t mean it’s smart to eat nothing but carbs and then go for a two-mile run.

Rawson advised that people only need to carb load when preparing for an endurance activity that is going to last at least 90-minutes. Anything shorter than it may be necessary to have that much fuel.

Photo by Pablo Merchán Montes on Unsplash.

The Canadian-based dietitian and runner who has completed four marathons said that the right way to carb load is to really head closer to that 65 percent of calories coming from carbs in a day (throughout the entire day) when preparing for a big race like a marathon.

“You don’t want to hit the wall,” she said. “That’s what the whole point of carb loading is—making sure you have enough energy stored up to complete the distance. Anyone who has ever had that feeling or has been really tired during a run knows you’re going to feel better if you have carbs.”


  1. Grant Tinsley, PhD , Carb Loading: How to Do It + Common Mistakes, Health Website
  2. Dimity Mcdowell, The Right Way to Carb-Load Before a Race, Running Website