How Many Days Before an Event Should You Carb Load?

January 2, 2026 •

2 min read

The human body can only store enough glycogen to fuel approximately 90 minutes of high-intensity exercise. Therefore, for events lasting longer, the strategic practice of carbohydrate loading becomes essential to maximize energy reserves and prevent 'hitting the wall'.

Quick Summary

The ideal carb loading window for endurance events is 1 to 3 days before a race, combined with a training taper. This strategy focuses on increasing carbohydrate intake while decreasing exercise to maximize muscle glycogen stores for enhanced performance and delayed fatigue.

Key Points

Timing is 1-3 days before the event: A 24 to 72-hour period is the modern standard for effective carb loading, combined with reduced training.
Aim for 10-12g of carbs per kg of body weight: This is the recommended daily intake for optimal glycogen supercompensation during the loading phase.
Choose low-fiber, familiar foods: Stick to easily digestible carbs like white pasta, rice, and bagels to avoid gastrointestinal issues on race day.
Stay hydrated: Adequate water intake is essential during the loading process, as glycogen is stored with water in the muscles.
Reduce training volume: Tapering your exercise during the carb loading period ensures that your muscles can maximize glycogen storage.
Practice the strategy during training: Never test a new carb loading plan on race day. Practice with your food and hydration during your long training runs.

Timing Is Everything: The Modern Approach to Carb Loading

Modern sports nutrition research indicates that a shorter, more targeted approach to carb loading is effective without the depletion phase used in older methods. The current recommendation for athletes in endurance events is a 1 to 3-day high-carbohydrate period, timed with a training taper.

The 24–48 Hour Protocol

For many endurance events, a 24 to 48-hour carb loading window is sufficient. This involves increasing carbohydrate intake to approximately 10–12 grams per kilogram of body weight per day. To avoid discomfort, this intake should be spread across meals and snacks. Foods should be easily digestible and low in fat and fiber to prevent gastrointestinal issues during the event.

The 3-Day Method for Maximum Supercompensation

Some athletes prefer a 3-day approach, which can potentially lead to slightly higher muscle glycogen levels (supercompensation). This involves gradually increasing carbohydrate intake while decreasing training. A possible structure for a Sunday race is:

Day 3 Out (Thursday): Moderate to high carbohydrate intake (7–8g/kg) with reduced training. Day 2 Out (Friday): Higher carbohydrate intake (10–12g/kg) with very light or no training. Day 1 Out (Saturday): Continued high carbohydrate intake and rest.

What to Eat and What to Avoid

Selecting easily digestible, low-fiber foods is key for effective carb loading to prevent stomach upset. Avoid experimenting with new foods close to your event.

Ideal Carb Loading Foods:

White Pasta and Rice
Plain Bagels and White Bread
Oatmeal
Potatoes and Sweet Potatoes (without skin)
Fruit Juices and Sports Drinks
Energy Gels and Chews

What to Avoid:

High-Fiber Foods (raw vegetables, legumes, whole grains)
High-Fat Foods (fatty meats, sauces)
Spicy Foods
Alcohol

Carb Loading Strategy Comparison Table

The full Carb Loading Strategy Comparison Table can be found on {Link: STYRKR https://styrkr.com/blogs/training-and-nutrition-hub/carb-loading-before-marathon}.

Common Carb Loading Mistakes to Avoid

Waiting until the night before: One large meal is less effective than spreading intake over 1-3 days.
Eating too much fiber: This can cause GI issues; refined grains are better during this period.
Forgetting to hydrate: Glycogen storage requires water, so fluid intake is vital.
Not tapering exercise: Maintaining intense training prevents effective glycogen storage.
Trying new foods: Test your loading strategy in training to avoid race-day stomach issues.

Conclusion: Fuel Your Performance Right

For most endurance events over 90 minutes, a 1 to 3-day high-carbohydrate protocol, combined with a taper and focus on easily digestible foods and hydration, is the recommended modern approach to maximize glycogen stores for optimal performance. Individual needs and tolerance should guide the specific strategy.

About the Author

[Disclaimer: The author of this article is a content creator, and this content is for informational purposes only. Readers should consult with a sports nutritionist or healthcare professional before beginning any new nutritional strategy.]

Frequently Asked Questions

Most experts recommend consuming 10–12 grams of carbohydrates per kilogram of body weight per day during the carb loading phase, typically the 1-3 days before an event.

Yes, research suggests that a one-day, high-intensity carb load (24-36 hours) can be effective for topping off glycogen stores, especially when combined with a proper taper.

It is best to avoid high-fiber foods, high-fat foods, and anything unfamiliar or spicy during the carb loading period to minimize the risk of digestive issues during your event.

Yes, temporary weight gain of 1–2kg is normal during carb loading. This is due to the extra water stored with the glycogen and is a sign that your loading is effective.

Carb loading is generally not necessary for events shorter than 90 minutes. For a 5k or 10k, a normal, well-balanced diet should provide sufficient energy.

To prevent bloating, spread your carbohydrate intake across multiple smaller meals throughout the day instead of one large meal. Stick to easily digestible, low-fiber carbs.

While the focus is on carbs, you don't need to eliminate protein and fat entirely. Include moderate amounts of lean protein and healthy fats, but reduce overall intake to prioritize carbohydrates.

Relying on just one large pasta dinner the night before a race is not the best strategy. Effective carb loading involves a sustained, multi-day increase in carbohydrate intake to fully saturate glycogen stores.