How many carbs to eat for carbo loading: A guide for endurance athletes

November 9, 2025 •

3 min read

Research has shown that effective carbohydrate loading can increase glycogen stores by up to 50%, significantly improving performance and delaying fatigue in endurance events lasting over 90 minutes. But the question remains, how many carbs to eat for carbo loading to achieve this optimal fueling strategy?

Quick Summary

This guide provides detailed recommendations on the daily carbohydrate intake required for effective carb loading, including per-kilogram calculations for different athletes. It explores the timing, food choices, and common mistakes to avoid, ensuring maximum glycogen storage and peak performance for your next endurance event.

Key Points

Target 7-12 g/kg/bw: Consume this amount of carbohydrates per kilogram of body weight, depending on the event length.
Start 1-3 days before: The optimal carb loading period is 1 to 3 days prior to your endurance event.
Focus on low-fiber carbs: Choose easily digestible, low-fiber sources like white pasta, rice, and bagels to avoid gastrointestinal issues.
Taper training volume: Reduce training intensity and volume during the loading phase to maximize glycogen storage.
Practice your plan: Test your carb loading strategy during long training runs to find what works best for your body.
Increase fluid intake: Glycogen binds to water, so increase your hydration during the loading phase.
It's not about overeating: The goal is to shift your macronutrient intake towards more carbohydrates, not to dramatically increase total calorie consumption.

Calculating Your Carbohydrate Needs

Determining the right amount of carbohydrates for carbo loading depends primarily on an athlete's body weight and the intensity of the event. For endurance events longer than 90 minutes, athletes typically aim for 7 to 10 grams of carbohydrates per kilogram of body weight (g/kg/bw) daily. Some protocols for events over two hours suggest 10 to 12 g/kg/bw. This loading phase usually occurs two to three days before competition, coinciding with a reduction in training volume.

For a 70kg athlete, this would mean consuming 490 to 700 grams of carbohydrates per day. Distributing this intake across multiple meals and snacks is recommended. Focus on high-carb, low-fiber sources to optimize glycogen storage and minimize digestive issues on race day.

The Science of Glycogen Supercompensation

Carbohydrates are converted to glucose and stored as glycogen in muscles and the liver, serving as a primary fuel during prolonged exercise. Carb loading enhances the body's glycogen storage capacity by increasing carb intake during a period of reduced training, a process known as 'supercompensation'. This boosts energy reserves, helping athletes sustain effort longer. This strategy involves adjusting macronutrient ratios to favor carbs, not simply overeating.

Modern vs. Classic Carb Loading Protocols

The classic approach involved a glycogen depletion phase with low-carb dieting and intense exercise, followed by high-carb intake. However, modern methods skip the depletion phase, which can cause fatigue, and focus on increasing carbohydrate intake during tapering. This simpler approach achieves similar glycogen benefits without the discomfort of the older method.

Comparison of Carb Loading Strategies


Feature	Modern 1-2 Day Protocol	Traditional 3-6 Day Protocol
Duration	1 to 2 days	3 to 6 days
Carb Intake	High (10-12 g/kg/bw)	Lower, but still high (7-10 g/kg/bw)
Depletion Phase	No	Yes (preceded by high-intensity exercise)
Training Taper	Required	Required
Digestitive Impact	Less risk of GI distress	Higher risk of discomfort from depletion and large intake
Psychological Impact	Less stressful	Can be more stressful and fatiguing

What to Eat and What to Avoid

Opt for easily digestible, low-fiber carbohydrates to prevent stomach upset. Suitable foods include white pasta, rice, white bread, and bagels. Sports drinks, gels, and juices can also contribute to carb intake. Reduce high-fat foods that can slow digestion. Avoid high-fiber foods like whole grains in the 24-48 hours before the event.

A Sample Carb Loading Day for a 70kg Athlete (Aiming for 700g)

Breakfast (approx. 150g carbs): Two bagels with jam or honey, fruit juice.
Mid-morning snack (approx. 100g carbs): A large banana and an energy bar.
Lunch (approx. 200g carbs): White pasta with low-fat tomato sauce.
Mid-afternoon snack (approx. 100g carbs): Low-fiber cereal or electrolyte drink.
Dinner (approx. 150g carbs): White rice with lean protein and low-fiber vegetables.

Conclusion: Fueling for Success

Knowing how many carbs to eat for carbo loading is vital for endurance athletes. The modern 1 to 2-day high-carb approach with tapering is effective and more comfortable than older methods. Aiming for 7-12 g/kg/bw of easily digestible carbs, reducing fiber and fat, and staying hydrated ensures optimal glycogen stores. Practice your fueling strategy during training for best results. Consult a sports dietitian for personalized advice. Effective carb loading requires careful preparation. https://www.mysportscience.com/post/carb-loading

Note: Individual needs vary. Practice is essential. Consult a healthcare professional or sports nutritionist for personalized advice, especially with existing health conditions.

Frequently Asked Questions

The optimal amount is generally 7 to 10 grams of carbohydrates per kilogram of body weight per day for two to three days before an endurance event. For events over two hours, some sources recommend 10 to 12 g/kg/bw.

You should start increasing your carbohydrate intake approximately two to three days before your endurance race to give your body enough time to fully stock glycogen stores in your muscles and liver.

The best foods are easily digestible, low-fiber carbohydrates. Examples include white pasta, white rice, bagels, pancakes, white bread, energy drinks, and fruit juice.

No, carb loading is not necessary for shorter events like a 5K. The strategy is most effective for endurance events lasting 90 minutes or longer, where your body's glycogen stores are more likely to become depleted.

Yes, it is generally recommended to reduce fiber intake in the final 24-48 hours before an event. High-fiber foods can cause digestive issues and bloating during your race.

You may experience a slight weight gain of 1-2kg and feel a little heavier. This is due to the water that binds with stored glycogen and is a sign that your body is effectively loading fuel. This feeling typically doesn't negatively impact performance.

Yes, carb loading only provides a larger initial reserve. You will still need to consume carbohydrates during the race to replenish glycogen stores and maintain energy levels, especially in events lasting longer than 90 minutes.