How to Carb Load Before Race Day

By Haleigh Hockenberry ·


If you've ever attended a pre-race pasta dinner, you've already seen carb loading in action. For decades, endurance runners have increased their carbohydrate intake before races to maximize energy stores and improve performance.

But carb loading is often misunderstood. Many runners think it means eating as much pasta as possible the night before a race. In reality, effective carb loading is a structured strategy that starts several days before a long endurance event.


When done correctly, carb loading can help runners avoid "hitting the wall" and maintain their pace deeper into a race.


What Is Carb Loading?


Carbohydrates are stored in your muscles and liver as glycogen. Glycogen is your body's preferred fuel source during moderate to high-intensity exercise.


As you run, these glycogen stores gradually decrease. Once they become depleted, your body must rely more heavily on fat for fuel, which is a slower and less efficient energy source. This is often the point where runners experience extreme fatigue, commonly known as "the wall."


Carb loading aims to maximize glycogen stores before a race so you have more readily available energy during long efforts.


Who Should Carb Load?


Carb loading is most beneficial for events lasting longer than 90 minutes.

Examples include:



For shorter runs, such as a 5K or easy daily training session, carb loading is generally unnecessary.


When Should You Start Carb Loading?


Most sports nutrition experts recommend increasing carbohydrate intake 2–3 days before a marathon or half marathon. During this period, carbohydrates should make up a larger percentage of your total calories while training volume decreases due to tapering.


The goal is not necessarily to eat dramatically more food overall, but to shift more of your plate toward carbohydrate-rich foods.


Best Foods for Carb Loading


Good carb-loading foods include:



In the final days before a race, many runners also reduce high-fiber foods to minimize gastrointestinal issues. White rice, white bread, and simple carbohydrates are often easier to digest than large amounts of vegetables or whole grains.


Practice Before Race Day


One of the biggest mistakes runners make is trying carb loading for the first time before an important race.


Experienced runners and coaches frequently recommend practicing your carb-loading strategy before long training runs. This helps you learn how your stomach reacts and allows you to fine-tune your nutrition plan. Many runners in marathon communities report that gut comfort matters just as much as hitting a specific carbohydrate target.


Carb Loading Is Only Part of the Plan


Carb loading helps fill glycogen stores, but it does not replace race-day fueling. According to Runner's World's guide to carb loading for endurance athletes, increasing carbohydrate intake in the days before a race helps maximize glycogen storage, but it must still be paired with proper fueling during the race itself for best performance.


Many marathon nutrition experts recommend consuming carbohydrates during long races through gels, chews, or sports drinks. Practicing this strategy during training is just as important as carb loading itself. Healthline explains that combining carb loading with in-race carbohydrate intake helps maintain energy levels and delay fatigue during prolonged endurance exercise.


The Bottom Line


Carb loading is a proven endurance strategy that helps runners maximize glycogen stores before long races and training efforts. When combined with proper hydration, race-day fueling, and a well-structured training plan, it can help improve performance and reduce the likelihood of hitting the wall.


The key is to start a few days before your event, focus on easily digestible carbohydrate sources, and practice your approach during training so there are no surprises on race day.