How Many Carbs Are Considered Carbo Loading? The Ultimate Guide for Endurance Athletes

November 9, 2025 •

3 min read

For endurance events over 90 minutes, your body's glycogen stores are your primary fuel source, and research shows that high muscle glycogen content can significantly increase the time to fatigue during exertion. Understanding how many carbs are considered carbo loading is the key to maximizing these reserves and achieving peak performance.

Quick Summary

This guide details the carbohydrate intake required for effective loading, typically 6-12 grams per kilogram of body weight for 1-3 days before an event. It covers the modern, taper-focused approach, optimal food choices, and timing strategies for maximizing glycogen stores and improving endurance.

Key Points

Target Carb Intake: Consume 6-12 grams of carbohydrates per kilogram of body weight per day during the loading phase.
Timing is Key: Start your carb load 1-3 days before a prolonged endurance event, not just the night before.
Focus on Low Fiber: Choose low-fiber, easily digestible carbs like white rice, pasta, and potatoes to avoid stomach upset.
Stay Hydrated: Drink plenty of fluids, as glycogen stores require water to be properly stored in your muscles.
Taper Your Training: Reduce your training volume while increasing carb intake to maximize glycogen storage.
Practice During Training: Never try a new carb-loading strategy on race day; practice it during your longest training runs.
Eat Little and Often: Spread your carb intake throughout the day with regular meals and snacks to avoid feeling bloated or uncomfortably full.

The Science Behind Carb Loading

Carbohydrates are the body's preferred source of fuel for high-intensity and prolonged exercise. They are converted to glucose and stored as glycogen in muscles and the liver. During endurance events over 90 minutes, these stores deplete, leading to fatigue, often called "hitting the wall". Carb loading strategically increases these stores to delay fatigue and improve performance.

How Many Carbs for Carbo Loading?

Recommended intake varies based on body weight and event duration. Sports nutrition guidelines suggest consuming 6-12 grams of carbohydrates per kilogram of body weight per day during the loading period. For example, a 70kg runner would aim for 420-840 grams daily. For females, some recommendations are slightly lower at 5-8 g/kg per day. Higher intakes are for longer, more intense events.

Modern vs. Classic Carb Loading Methods

The traditional "classic" method involved a depletion phase followed by a loading phase. Modern research favors a simpler approach: increasing carb intake to 6-12 g/kg/day for 1-3 days before the event while tapering exercise. This avoids the stress of depletion and effectively increases glycogen stores.

Timing, Food Choices, and Meal Planning

Optimal carb loading involves more than just total intake; timing and food types are key for absorption and avoiding discomfort on race day.

Best Practices for Your Carb Load:

Duration: Start 1-3 days before the race.
Food Choices: Choose easily digestible, low-fiber carbs like white pasta, rice, bagels, potatoes, and bananas.
Meal Distribution: Spread carb intake across multiple meals and snacks. Include snacks like pretzels or fruit juice.
Reduce Fat and Fiber: Decrease fat and protein intake to manage calorie load and aid digestion.
Hydration is Critical: Stay well-hydrated, as glycogen storage requires water.

Race Day Morning

A high-carb breakfast 2-4 hours before the race is necessary to replenish liver glycogen stores depleted overnight. Aim for 1-4 g/kg of carbs and use tested foods.

Comparison of Food Choices for Carb Loading


Food Type	Example Foods	Fiber Level	Digestion Rate	Best Use for Carb Loading
Low-Fiber Carbs	White pasta, white rice, bagels, sports drinks, low-fiber cereal, potatoes (peeled)	Low	Fast	Ideal. Minimizes GI distress and maximizes glycogen storage close to the event.
High-Fiber Carbs	Whole grain bread/pasta, brown rice, lentils, beans, high-fiber cereal	High	Slow	Limit. Best for general training, but can cause bloating and discomfort when loading.
Simple Sugars	Fruit juice, energy gels/chews, honey, dried fruit	Varies	Very Fast	Use strategically. Excellent for quick top-ups during the day or pre-race, but don't rely solely on them.
High-Fat Foods	Creamy sauces, pizza, fries, pastries, rich desserts	Low	Slow	Avoid. High fat intake can displace valuable carbohydrates and lead to unwanted weight gain.

The Final Word

Knowing how many carbs are considered carbo loading is vital for endurance athletes. For events over 90 minutes, consuming 6-12 grams of carbohydrates per kilogram of body weight for 1-3 days while tapering is the recommended approach. Prioritizing low-fiber, high-carb foods and staying hydrated helps maximize glycogen stores and performance. Always practice your strategy during training.

This article is for informational purposes only. Consult a registered dietitian or healthcare professional for personalized advice. Learn more about sports nutrition and performance with the National Strength and Conditioning Association (NSCA).

Frequently Asked Questions

Carb loading is generally not necessary for events shorter than 90 minutes, such as a 5k or 10k. Your normal glycogen stores are typically sufficient for these distances.

You may gain 1-2 kg of body weight during carb loading, but this is primarily water stored alongside glycogen, not fat. This weight is beneficial, as it means you are well-hydrated and your fuel tanks are full.

Spread your meals throughout the day, focusing on low-fiber, high-carb options. You can add extra carbs by increasing portion sizes of rice or pasta, drinking fruit juice, or having frequent carb-rich snacks like pretzels or energy bars.

Yes, you should still include some lean protein and healthy fats, but in reduced amounts. The goal is to shift your macronutrient ratio to favor carbohydrates without dramatically increasing your total calorie intake.

Yes, studies show both men and women can effectively carb load, though some women may need to consume a slightly higher relative amount of carbohydrates to achieve similar glycogen increases. Testing your protocol in training is key.

Eating too much fiber during the carb loading phase can lead to gastrointestinal distress, such as bloating, cramping, or diarrhea, on race day. It's best to switch to low-fiber carb sources in the days leading up to your event.

Yes, liquid carbohydrate sources like sports drinks, fruit juice, and energy gels are an excellent way to help meet your high carb goals without feeling overly full. They are also easily digestible.