What is a typical carbohydrate loading regimen for endurance athletes?

October 6, 2025 •

4 min read

For endurance events lasting over 90 minutes, such as marathons and triathlons, a strategic dietary approach can significantly enhance performance and delay fatigue. This strategy is known as carbohydrate loading, and understanding what is a typical carbohydrate loading regimen is crucial for any serious endurance athlete.

Quick Summary

A typical carbohydrate loading regimen involves increasing carb intake to 8–12 grams per kilogram of body weight in the one to three days leading up to an endurance event, combined with reduced training volume, to maximize muscle glycogen stores for sustained energy.

Key Points

Modern Approach: A typical carb loading regimen lasts 1–3 days before an endurance event and does not require a stressful depletion phase.
Fuel Target: Aim to consume 8–12 grams of carbohydrates per kilogram of body weight each day during the loading phase.
Optimal Foods: Focus on easily digestible, low-fiber, and low-fat carbohydrates like white rice, pasta, potatoes, and sports drinks.
Training Taper: Reduce your training volume and intensity in the days leading up to the event to allow muscles to maximize glycogen storage.
Hydration is Key: Glycogen is stored with water, so maintain adequate fluid intake throughout the loading period.
Practice Makes Perfect: Test your carb-loading strategy during long training sessions to avoid any surprises on race day.

The Science Behind Carb Loading

Carbohydrates are the body's primary fuel source during high-intensity and long-duration exercise. When consumed, carbohydrates are broken down into glucose and stored as glycogen primarily in the muscles and liver. For events like marathons, the body relies heavily on these glycogen reserves. However, muscle glycogen stores are limited and can be depleted in as little as 90 minutes of intense activity, a phenomenon commonly known as "hitting the wall".

Carbohydrate loading is a nutritional strategy that enables the body to store glycogen at levels higher than normal, a state called "glycogen supercompensation". This super-charged fuel tank can boost endurance by 15–25% and delay the onset of fatigue.

What is a typical carbohydrate loading regimen?

Gone are the days of the rigorous six-day regimen that involved a taxing depletion phase. Modern research has shown that a simpler, shorter, and less stressful approach is just as effective. A typical and highly recommended regimen lasts for one to three days leading up to the event and involves two key components: dietary changes and training taper.

Modern 1-3 Day Regimen

Duration: Begins approximately 36 to 72 hours before the event.
Carbohydrate Intake: Consume 8–12 grams of carbohydrate per kilogram of body weight per day. For example, a 70kg (154 lb) athlete would aim for 560 to 840 grams of carbs daily.
Training Taper: Reduce training volume and intensity significantly or take complete rest days to conserve energy and allow muscles to absorb the extra glycogen.

Choosing the Right Foods

To hit high carbohydrate targets without causing gastrointestinal distress, it is important to focus on easily digestible, lower-fiber, and lower-fat options.

Recommended High-Carb Foods

Grains: White pasta, white rice, bagels, white bread, low-fiber cereals like cornflakes or rice krispies.
Starches: Potatoes, sweet potatoes (without the skin), and low-fat crackers.
Fruits: Bananas, grapes, fruit juices, and dried fruits like raisins or dates.
Drinks & Gels: Sports drinks, energy gels, and smoothies can help meet carb goals without the bulk of solid food.
Snacks: Rice cakes, pretzels, and low-fat muffins.

Foods to Limit or Avoid

High-Fiber: Legumes, beans, high-fiber cereals, and most raw vegetables. Excessive fiber can cause bloating and discomfort during the race.
High-Fat: Creamy sauces, buttery toppings, and fried foods. Fat slows digestion and takes up stomach space that should be used for carbohydrates.
Novel Foods: Avoid introducing new or unusual foods close to race day to prevent unexpected digestive issues.

Classic vs. Modified Carb Loading

Understanding the evolution of carb loading strategies can help explain why the modern approach is preferred. The following table highlights the key differences.


Feature	Classic (6-Day) Regimen	Modified (1–3 Day) Regimen	Primary Benefit	Modern Preference
Duration	6 days	1–3 days	Shorter duration, less stress	Yes
Depletion Phase	3–4 days of low-carb diet and intense exercise	None required	Avoids discomfort and fatigue of depletion phase	Yes
Carb Intake	3 days low carb, 3 days high carb (>70% total calories)	8–12 g/kg body weight per day	More focused and precise fueling	Yes
Training	High intensity during depletion, rest during loading	Tapered training throughout	Allows for better recovery and reduced injury risk	Yes
Side Effects	Often caused mood swings, fatigue, and injury risk	Minimal digestive issues if low-fiber foods are chosen	Fewer negative side effects	Yes

Practical Tips for Your Regimen

To execute a successful carb-loading regimen, consider these practical tips:

Practice with Your Food: Always experiment with your chosen carb-loading foods and drinks during training cycles, especially before long runs, to determine what works best for your body.
Spread Out Your Intake: Instead of consuming massive meals that can cause bloating, distribute your carbohydrate intake throughout the day with regular meals and snacks.
Hydrate Adequately: Glycogen stores water with it, so staying well-hydrated is essential. This water weight, typically 1–2 kg, is a normal and beneficial part of the process and will be used during your event.
Don't Just Add Calories: The goal is to substitute fat and some protein calories for carbohydrates, not simply add more total food. This prevents unnecessary weight gain and digestive issues.
Listen to Your Body: Carb loading is not a one-size-fits-all plan. Adjust the amount and timing based on your personal tolerance and how you feel.

Conclusion

For endurance athletes, implementing a typical carbohydrate loading regimen is a proven method to increase muscle glycogen stores and optimize performance. The modern 1–3 day approach, focusing on high carbohydrate intake (8–12 g/kg body weight) and tapered training, has largely replaced the older, more stressful depletion method. By prioritizing easily digestible, low-fiber carbohydrate sources and staying well-hydrated, athletes can effectively fuel their bodies for events lasting over 90 minutes. Consistent practice during training is the final and most important step to ensure a smooth and successful execution on race day.

Explore more on sports nutrition from the American College of Sports Medicine

Frequently Asked Questions

Carb loading is most beneficial for endurance athletes competing in events lasting 90 minutes or longer, such as marathons, triathlons, and long-distance cycling.

A modern, typical regimen starts one to three days (approximately 36–72 hours) before your endurance event.

Experts recommend a daily intake of 8–12 grams of carbohydrate per kilogram of body weight during the loading phase, depending on individual needs.

No, but you should reduce your intake of fat and moderate your protein to make room for the higher volume of carbohydrates. Choose lean protein sources and minimize high-fat foods.

While a large pasta meal is a classic image, it is more effective to distribute your increased carb intake across multiple smaller meals throughout the one to three days leading up to the event. This prevents bloating and aids digestion.

You may experience a temporary weight gain of 1–2 kg. This is a positive sign that your body is storing extra glycogen, which binds with water.

During the loading phase, white rice is often preferred over brown rice. It is lower in fiber and easier to digest, which helps minimize the risk of gastrointestinal issues on race day.

If you struggle to consume enough solid carbohydrates, liquid sources such as sports drinks, fruit juices, and smoothies can be excellent alternatives to help meet your target intake.