Before a race, it's essential to maximize your energy stores, and carbs play a key role in that. During exercise, carbs are mainly digested in the small intestine, where they’re turned into glucose and absorbed to fuel your muscles. This glucose can be used immediately or stored as glycogen in your muscles and liver, ready to be tapped into during your race.

That’s where carb loading comes in: a well-known nutrition strategy used by endurance athletes to boost glycogen stores ahead of a big effort.

What is carb loading?

Carb loading means increasing your carbohydrate intake in the days leading up to a race to maximize your glycogen reserves, your body’s energy storage system. But be careful: if done wrong, it can do more harm than good. Think digestive issues, fatigue, or unnecessary calorie overload. It’s all about getting the method right to reap the benefits without the downsides.

This guide breaks down how carb loading works, how to apply it, and the key mistakes to avoid so you can show up ready on race day.

How the body uses glycogen during endurance efforts ?

At the start of an effort, the body first uses blood glucose as immediate energy. As the activity continues, the body's muscle glycogen stores are used to provide energy. As the intensity or duration of the exercise increases, glycogen stores in the muscles and liver gradually decrease. Once these stores are depleted, the body then turns to fat as an energy source, which is a slower and more tiring process.

By consuming carbohydrates during exercise, the body can maintain a steady energy supply, helping to prevent a significant drop in muscle glycogen and blood glucose levels. This helps you keep a solid pace and avoid that dreaded “wall” that hits when your glycogen is gone.

How to maximize carbohydrate stores?

Carb loading involves increasing your carbohydrate intake in the days leading up to a race. It’s generally recommended to consume between 8 and 12 grams of carbohydratesper kilogram of body weight per day. For example, for someone weighing 70 kg, this means between 560 and 840 grams of carbohydrates per day, spread out through meals with foods like rice, pasta, and potatoes, fruits, and juices throughout the day.

This amount can vary depending on the individual, the duration, and the intensity of the planned workout. It’s important to adjust according to your personal tolerances.

The goal of carb loading is to increase your daily carbohydrate intake while slightly reducing fat and protein consumption, in order to maximize muscle and liver glycogen stores.

At the same time,it’s essential to reduce the intensity and volume of training in the days before the race. Continuing intense workouts during this period can lead to ongoing glycogen depletion, which reduces the effectiveness of carb loading. By opting for rest periods or light training, you allow your muscles and liver to store more glycogen, ensuring better performance and optimal energy output on race day.

How to carb load effectively

1. When should you Start?

To be effective, carb loading should begin about 2 to 3 days before your race. That’s the window when your body is best able to store glycogen. Loading for longer than that won’t give you any extra benefit because your body’s capacity maxes out.

2. What foods are best?

Go for easy-to-digest, simple carbs like white rice, white pasta, white bread, potatoes, and low-fiber fruits like ripe bananas or grapes.

These are quickly digested and absorbed, helping you top up your glycogen without upsetting your stomach. Drink Mixes and bars can also be useful for adding carbs without making meals too heavy.

3. What foods to avoid

Just as important is knowing what not to eat in the days leading up to your race.

Avoid greasy, high-fat foods like fried dishes, heavy sauces, processed meats, fast food, pastries, chips, and hard cheeses. These slow down digestion and reduce your body’s ability to absorb carbs, hurting your carb loading efforts.

Also, steer clear of high-fiber foods like vegetables, whole grains, and cruciferous vegetables (like broccoli and cabbage). While normally great for health, too much fiber before a race can lead to bloating and digestive discomfort.

Lastly, while protein is essential for muscle recovery, eating too much, especially red meat or dairy can slow digestion. Stick to lighter options like chicken, turkey, fish, eggs, or tofu. Too much protein can also crowd out the space for carbs in your meals, making your carb loading less effective.

4. Sample carb loading meal plan

The best approach is to eat small, frequent meals every 2–3 hours, making it easier for your body to absorb carbs without feeling heavy.

Here’s a sample breakfast and full-day meal plan for a carb loading day:

Common carb loading mistakes

There are a lot of myths out there about carb loading. Let’s bust a few:

“One big pasta meal is enough.”

Reality: Carb loading isn’t just about one meal. It requires several days of gradually increasing carbohydrate intake to maximize glycogen stores. A single meal isn’t enough to fully replenish your stores.

“Just focus on carbs, skip the fats and proteins.”

Reality: While the main goal is to increase carbohydrates,it’s important not to ignore proteins and fats. These nutrients are essential for maintaining overall nutritional balance. A diet too focused on carbohydrates, at the expense of other nutrients, can lead to nutritional imbalances and affect your digestive health.

“Carb loading works for all sports.”

Reality: While carb loadingis ideal for endurance efforts lasting more than 90 minutes, it’s not as useful for short efforts. For short-duration activities, your glycogen stores are typically not used significantly, making the overload unnecessary.

Possible side effects and how to avoid them

Carb loading can cause some side effects, but don't worry! They are usually temporary and can be avoided by following the right practices.

Bloating and Digestive Discomfort

Some carb-rich foods, especially whole grains or high-fiber veggies can be harder to digest when eaten in large quantities. Reducing fiber intake before race day can help prevent bloating or GI discomfort during your effort.

Feeling of heaviness, fatigue, and weight gain before the race

Carb loading, combined with a decrease in physical activity, leads to water retention, which can cause a feeling of heaviness or fatigue. In fact, for every gram of glycogen stored, the body retains about 2 to 4 grams of water. This can result in a slight weight gain, which is completely normal.

Hydration is even essential, as glycogen is stored in the muscles and liver along with water. This extra weight gain is therefore temporary and is part of the process of maximizing your energy reserves before the race.

Conclusion

When done right, carb loading can give you a serious performance boost on race day. Stick to the key principles, avoid common mistakes, and you’ll show up well-fueled and ready to go.

Now it’s your turn, let’s make all that prep count!