Carbohydrate loading requires more than simply eating extra carbohydrates; it involves strategic planning around both nutrition and training in the days leading up to an endurance event. When done thoughtfully, it can significantly increase muscle glycogen stores, delay fatigue, and improve performance. However, when executed poorly, whether due to eating the wrong types of carbs, overdoing fiber, or neglecting to modify workout intensity, it may lead to bloating, GI discomfort, and a sluggish race-day experience.  

 

In our previous blog, we reviewed what carbohydrate loading is and who stands to benefit most from it. Here, we shift the focus from theory to practice, focusing on how to implement it effectively.  

 

When to Start Carb Loading

 

When to start carb loading depends on the approach you follow. Most endurance athletes increase their carbohydrate intake from 40 to 50% to about 70 to 80% of total calories starting 3 days before the event, while tapering their training [1]. The classic 6-day method begins earlier: athletes continue following a normal diet (consuming a mix of all 3 macronutrients) and reduce training during the first 3 days, then switch to a high-carb diet for the last 3 days [1]. Alternatively, recent research supports a shorter, 1-day loading strategy, where athletes complete an intense workout 2 days before the event, then rest and consume very high carbohydrates (around 10 grams per kilogram of body weight) the following day [1]. Regardless of the method, maintaining a high-carb intake through the day before the event helps ensure glycogen stores remain fully replenished for peak performance.

 

The Importance of Tapering Increasing carbohydrate intake alone isn’t enough to fully maximize glycogen stores; it’s equally important to adjust your training in the days preceding your event. Focus on short, low-intensity sessions to limit glycogen depletion, preserve neuromuscular function, and allow your muscles to recover. Avoid prolonged or intense workouts during this period, as they can interfere with glycogen replenishment and reduce the effectiveness of carb loading.

 

How Much Carbohydrate to Eat

While carb loading, aim for 3.6 to 5.5 grams per pound (8 to 12 grams per kilogram) of carbohydrate each day [2,3]. For example, a 154 lb (70 kg) athlete would need about 560 to 840 grams of carbs daily. Spread this intake over several meals and snacks. 

 

Best Foods to Eat During Carb Loading

When it comes to increasing glycogen reserves, focus on carbohydrates that are lower in fiber (aka easily digestible). These choices are less likely to cause digestive discomfort (i.e., gas, bloating, cramping), especially when consumed in larger amounts or within 24 hours of your event:

 

• White rice
• White pasta
• White bread, bagels
• Cereal (<2 grams fiber per serving), such as Rice Chex
• Potatoes
• Corn 
• Bananas
• Applesauce
• Smoothies 
• Sports drinks
• Pretzels
• Graham crackers
• Fruit juice
• Snack bars (low in fiber and low in fat), such as MadeGood Chocolate Chip Granola Bars

 

Understanding Carbohydrates: Simple vs. Complex Carbohydrates come in two main forms: simple and complex. Simple carbohydrates are sugars found in foods like fruit juice, honey, and candy. They digest quickly, providing immediate energy but often causing rapid blood sugar fluctuations.   Complex carbohydrates consist of longer chains of sugar molecules and include foods like whole wheat pasta, wild rice, and potatoes. While complex carbs generally digest more slowly, refined versions (i.e., white pasta or white rice) have most of their fiber removed, making them easier to digest and less likely to cause stomach discomfort compared to whole grains.   For effective carbohydrate loading, refined complex carbohydrates like white pasta are ideal because they provide an immediate source of sugar to store as glycogen and thus help fuel the muscles for a later time. You can also choose simple carbs, such as fruit juice or sports drinks!

 

Foods to Limit or Avoid

To minimize digestive issues, (especially in the 24 to 36 hours before your event), limit foods that can affect gut motility, cause bloating, or delay gastric emptying, such as:

 

• High fiber foods: whole grains, beans, lentils, raw vegetables
• High fat foods: fried items, creamy sauces, high fat cheeses
• Spicy foods: Tabasco sauce, curry, jalapeno peppers
• Cruciferous and Allium vegetables aka gas producing foods: onions, garlic, cruciferous vegetables (i.e., brussel sprouts, broccoli, cauliflower)
• Excessive protein: while some protein is important, prioritize getting 70% of your dietary intake from carbohydrates during this period

 

Don’t Forget to Hydrate!

 

Carbohydrate loading increases glycogen storage in muscle, drawing in about 3 grams of water for every gram of glycogen [1,3]. This promotes efficient muscle function but may also cause a normal, temporary weight gain. However, because this fluid shift occurs primarily inside muscle cells, it doesn’t fully reflect your overall hydration status. To avoid dehydration-related performance decrements, maintain consistent and adequate fluid intake in the days leading up to your event.

 

 

References

1. Sedlock DA. The Latest on Carbohydrate Loading. Current Sports Medicine Reports. 2008;7(4):209-213.
2. Mata F, Valenzuela PL, Gimenez J, et al. Carbohydrate Availability and Physical Performance: Physiological Overview and Practical Recommendations. Nutrients. 2019;11(5):1084. doi:https://doi.org/10.3390/nu11051084
3. Murray B, Rosenbloom C. Fundamentals of Glycogen Metabolism for Coaches and Athletes. Nutrition Reviews. 2018;76(4):243-259. doi:https://doi.org/10.1093/nutrit/nuy001
4. Coleman A. How to Carb Load Before Your Next Race. www.precisionhydration.com. Accessed July 9, 2025. https://www.precisionhydration.com/performance-advice/nutrition/how-to-carb-load-before-a-race/