How many carbs should you eat when carb loading?

January 3, 2026 •

4 min read

Endurance athletes who carb load can boost their performance by up to 2-3% and increase endurance by 15-25%, according to some studies. To achieve this, understanding how many carbs should you eat when carb loading is crucial for maximizing muscle glycogen stores and ensuring you have sufficient fuel for race day. This guide will break down the science and provide practical recommendations.

Quick Summary

This guide details the optimal carbohydrate intake for endurance athletes during carb loading, typically 7–12 grams per kilogram of body weight over 1–3 days. It covers food choices, modern versus classic loading methods, and crucial hydration strategies to maximize performance while minimizing gastrointestinal distress.

Key Points

Optimal Intake: Consume 7–12 grams of carbohydrates per kilogram of body weight per day during the 1–3 day carb-loading period.
Modern Method: Skip the old depletion phase. Focus on a 1–3 day high-carb approach paired with a reduced training taper.
Food Choices: Prioritize easily digestible, low-fiber carbs like white rice, pasta, and bagels in the final 48 hours to prevent stomach discomfort.
Fluid Intake: Increase fluid intake during carb loading, as every gram of stored glycogen holds extra water, which is vital for hydration.
Practice is Key: Test your carb-loading strategy during training runs or events to see how your body responds before race day.
Avoid Overeating: Focus on replacing fat and fiber with carbohydrates, rather than simply consuming more total calories, to avoid feeling sluggish.
Timing Matters: Spread your carb intake across multiple meals and snacks throughout the day, rather than one massive meal the night before.

Understanding the 'How Many' of Carb Loading

Carbohydrate loading is a well-established nutritional strategy designed to maximize glycogen stores in the muscles and liver before an endurance event lasting longer than 90 minutes. Glycogen is your body's most readily available fuel source for moderate to high-intensity exercise. By supercompensating your glycogen stores, you can delay fatigue and improve performance. The key is not to just eat more, but to strategically adjust your macronutrient intake alongside a reduced training load, or 'taper'.

Modern vs. Classic Carb Loading Strategies

For many years, the classic approach to carb loading involved a depletion phase, where athletes would significantly reduce carbohydrate intake for several days while maintaining a high training volume. This was followed by a 3-day high-carb phase and tapering exercise. However, modern research has shown that this depletion phase is unnecessary and can be stressful on the body. A simpler and more effective approach focuses solely on the high-carb phase combined with a reduced training volume.

The Modern 1–3 Day Carb Load

For most athletes, a 1–3 day carb loading protocol is sufficient. The exact amount of carbohydrates varies based on individual body weight and sport intensity.

General Guideline: Aim for 7–12 grams of carbohydrates per kilogram of body weight per day. For a 70kg (154 lb) athlete, this would mean consuming between 490g and 840g of carbohydrates daily.
Duration: The loading period should last 1–3 days leading up to the race. A shorter, more intense 1–2 day load of 10–12g/kg is recommended for maximum glycogen storage.
Simplicity: Replace some of your protein and fat intake with extra carbohydrates. The goal is to increase the percentage of calories from carbs, not just total calories.

Optimal Food Choices During Carb Loading

Choosing the right types of carbohydrates is vital for minimizing gastrointestinal issues and maximizing absorption. Low-fiber, easily digestible carbohydrates are often preferred during the final 24-48 hours before an event to avoid stomach discomfort.

Best Food Sources

White starches: White rice, white pasta, white bread, and bagels are excellent low-fiber options.
Sports nutrition products: Energy drinks, gels, and chews can help meet high carbohydrate targets without excessive bulk.
Low-fat dairy: Yogurt and low-fat milk can provide both carbs and some protein.
Fruit juices and low-fiber fruits: Juice without pulp, bananas, and canned fruits are easy to digest.
Breakfast cereals: Options like cornflakes or rice krispies are effective, especially with low-fat milk.
Potatoes: Peeled potatoes or sweet potatoes can be a great source of carbs.

Comparison of Carb Loading Protocols


Feature	Modern 1–3 Day Carb Load	Classic 6-Day Carb Load	Comment
Duration	1–3 days	6 days	Modern approach is shorter and simpler.
Depletion Phase	Not required	High-intensity exercise and low-carb diet for first 3 days.	Depletion phase is unnecessary and adds stress.
Carb Intake	High carb (7–12 g/kg/day) with reduced training.	High carb (>70% of calories) in the final 3 days.	Modern is based on body weight, providing a clearer target.
Gastrointestinal Risk	Lower, if low-fiber foods are used in final 24–48 hours.	Higher, due to abrupt dietary shifts and potential overeating.	Modern methods emphasize practicality and comfort.
Relevance	Suitable for most endurance events >90 minutes.	Largely considered outdated, though still practiced by some.	Modern protocols are evidence-based and athlete-friendly.

Common Mistakes to Avoid

Waiting until the last minute: A single large pasta meal the night before is not enough to maximize glycogen stores. Loading should begin 1–3 days prior. Waiting until the night before can cause GI upset and discomfort.
Neglecting hydration: For every gram of stored carbohydrate, you also store an extra 3 grams of water. Proper hydration is crucial for this process and overall race performance.
Overdoing fiber and fat: While typically healthy, high-fiber and high-fat foods can lead to digestive issues during the loading phase. Focus on easily digestible, low-fiber carbs.
Not practicing in training: Never try a new nutritional strategy on race day. Practice your carb loading on longer training runs to understand how your body reacts.
Neglecting protein: While carbs are the focus, don't eliminate protein entirely. A moderate amount is still needed for muscle repair and general bodily function.

Conclusion

For endurance events lasting over 90 minutes, a strategic carb-loading plan is a powerful tool to enhance performance. The recommended carb intake is approximately 7–12 grams per kilogram of body weight per day, spread across 1–3 days before your event. Focus on low-fiber, easily digestible carb sources while decreasing your fat and fiber intake to avoid stomach issues. Remember to practice your fuelling strategy during training, taper your exercise, and stay well-hydrated to ensure your glycogen stores are topped off for a successful race.

Visit the American College of Sports Medicine for more advanced sports nutrition guidelines.

Frequently Asked Questions

The recommended intake for carb loading is typically 7–12 grams of carbohydrates per kilogram of body weight per day. For a 70kg athlete, this translates to 490–840 grams of carbs daily.

You should start carb loading 1–3 days before your endurance event. Modern research indicates a 1–2 day period of high carbohydrate intake is effective and less stressful than longer protocols.

Easily digestible, low-fiber carbohydrates are best for carb loading, especially in the final 48 hours. Good examples include white pasta, white rice, bagels, energy gels, and fruit juices. Avoid high-fiber and high-fat foods that can cause GI upset.

No, relying on a single large pasta meal the night before is a common mistake and not sufficient. Effective carb loading requires consistent high carbohydrate intake over 1–3 days to fully maximize your glycogen stores.

Yes. Carb loading is most beneficial for endurance events lasting over 90 minutes. For shorter events like a 5k, a standard healthy diet with adequate carbs is typically sufficient, and aggressive loading isn't necessary.

It is normal to gain a small amount of weight (1–2 kg) during carb loading. This extra weight is primarily from water bound to the stored glycogen and is a positive sign that your fueling strategy is working.

The keys to successful carb loading are proper timing (1–3 days out), consuming the correct amount of carbs based on your weight (7–12 g/kg), choosing easily digestible foods, staying hydrated, and practicing the entire strategy before race day.