How to do Proper Carb Loading for Peak Performance

October 20, 2025 •

4 min read

Studies have shown that proper carb loading can improve endurance performance by up to 2-3%, significantly delaying the onset of fatigue during events lasting longer than 90 minutes. This critical sports nutrition strategy is used by endurance athletes to super-saturate their muscle glycogen stores before a major event, ensuring a robust energy reserve for race day.

Quick Summary

This guide provides a comprehensive breakdown of proper carb loading techniques, including modern timing strategies, optimal food choices, hydration practices, and how to avoid common pitfalls like bloating. It details how to calculate carbohydrate needs based on body weight and integrate this fuel strategy with a tapering training schedule for maximum performance.

Key Points

Modern Method: Forget the old depletion phase; a modern carb-load involves increasing intake for 2-3 days before an event alongside a reduced training taper.
Calculate Your Needs: Aim for 8-12 grams of carbohydrates per kilogram of body weight daily during the loading period to maximize glycogen stores.
Choose Low-Fiber Carbs: Opt for easily digestible, lower-fiber carbs like white pasta, rice, and bagels to prevent stomach discomfort and bloating on race day.
Stay Hydrated: Drink plenty of water and electrolytes, as extra water is stored with glycogen, contributing to a temporary but beneficial weight increase.
Practice During Training: Never try a new food or carb-loading strategy on race day; practice your plan during long training runs to test your body's response.
Eat Little and Often: Spread your carbohydrate intake across several small meals and snacks to make it easier to consume high volumes without feeling overly full.

The Science of Carb Loading

Carbohydrate loading, or 'carb loading', is a nutritional technique designed to maximize the storage of glycogen in your muscles and liver. Glycogen is the primary fuel source for high-intensity, long-duration exercise. An average athlete's body can store enough glycogen for about 90 minutes of intense effort. When glycogen stores are depleted, a feeling of extreme fatigue known as 'hitting the wall' occurs. Proper carb loading aims to prevent this by boosting your glycogen reserves, allowing you to sustain a higher intensity for longer.

Modern Carb Loading vs. The Classic Method

For many years, the classic carb-loading protocol involved a week-long process. It began with a glycogen depletion phase—a few days of hard exercise with a low carbohydrate intake—followed by several days of high carbohydrate consumption. However, modern sports nutrition has refined this approach, finding the depletion phase to be unnecessary and potentially detrimental. The most effective and widely-used method today focuses on increasing carbohydrate intake in the 2-3 days leading up to an event, alongside a reduced training load (tapering).

Timing and Tapering: The Dynamic Duo

For a major endurance event, your prep should begin with a training taper 4-5 days beforehand. This reduces the amount of glycogen you use in training, allowing your body to start storing it more effectively. The actual carb loading phase, where you significantly increase carbohydrate consumption, begins 2-3 days before the race. During this period, 85-95% of your daily calories should come from carbohydrates, while reducing protein and fat intake slightly to manage overall calorie load and avoid feeling overly full.

Calculating Your Carbohydrate Needs

To ensure you're consuming enough carbohydrates, you'll need to calculate your specific needs based on your body weight. Recommendations are typically given in grams of carbohydrates per kilogram of body weight (g/kg). For endurance events lasting over 90 minutes, the goal is often between 8 and 12 g/kg per day.

For example, a 70kg athlete aiming for 10g/kg per day would need to consume 700g of carbohydrates daily. Spreading this intake over several smaller, more frequent meals (5-6 meals per day) can make this easier to manage and prevent the feeling of being overly stuffed.

The Role of Hydration

Proper hydration is a non-negotiable part of carb loading. For every gram of stored glycogen, your body holds on to about 3 grams of water. This is why athletes may experience a slight weight gain during carb loading—it's a sign that your glycogen and water stores are being maximized. Staying well-hydrated throughout the loading phase and on race day is crucial for optimal performance. Drinking plenty of water or electrolyte-fortified sports drinks is essential.

Foods to Embrace and Avoid

Choosing the right types of carbohydrates is key to successful carb loading without gastrointestinal issues. Focus on easily digestible, moderate-to-high glycemic index carbohydrates. This means prioritizing refined grains over high-fiber whole grains in the final 48 hours to minimize bloating and stomach upset.

Good Carb Loading Foods

White pasta and rice
White bread and bagels
Oatmeal
Potatoes (without skin)
Bananas and fruit juice
Sports drinks, energy gels, and chews

Foods to Limit or Avoid

High-fiber foods (beans, broccoli, bran cereal)
High-fat foods (creamy sauces, fried foods, excess butter)
Excess protein (red meat, heavy protein shakes)

Carb Loading: Sample Meal Plan

This is a sample two-day plan for a 70kg athlete aiming for 700g of carbs per day. The key is to adapt it to your preferences while keeping fat and fiber low.


Meal	Day 1 (Approx. 700g carbs)	Day 2 (Approx. 700g carbs)
Breakfast	Large bowl of oatmeal with banana and honey. Large glass of fruit juice.	Bagel with jam and a large banana. Sports drink.
Morning Snack	Rice cakes with jam. Sports drink.	Low-fat yogurt with a handful of pretzels. Fruit juice.
Lunch	Large portion of white rice with lean chicken breast. Small amount of low-fat sauce.	Large portion of plain white pasta with tomato sauce. Small glass of fruit juice.
Afternoon Snack	Energy bar and a banana.	Rice pudding with maple syrup.
Dinner	Pasta with a low-fat tomato sauce and lean ground meat. White bread with honey.	Plain white rice with a mild chicken curry. Small side of potatoes.
Evening Snack	Cereal with low-fat milk.	Toast with honey.

The Morning of the Event

Your final meal should be 2-4 hours before the start. This should be a small, easily digestible, high-carbohydrate breakfast. Examples include a bagel with peanut butter or a bowl of oatmeal with a banana. Remember, nothing new on race day. Use a meal you have practiced with during your training.

Conclusion: Practice Makes Perfect

Carb loading is a refined science that can provide a significant performance edge in endurance events. By adopting the modern 2-3 day strategy, focusing on high-carbohydrate, low-fiber, and low-fat foods, and staying well-hydrated, you can maximize your glycogen stores and delay fatigue. Remember to practice your carb-loading strategy during your longest training runs to see what works best for your body and to avoid any race-day surprises. The payoff will be a race fueled by full energy reserves, allowing you to push harder and finish stronger. For more detailed information on nutrition strategies, consult a sports dietitian.

Frequently Asked Questions

The primary goal is to maximize the storage of glycogen in your muscles and liver, providing a super-sized energy reserve for high-intensity endurance events lasting longer than 90 minutes.

For optimal results, you should start the carb-loading phase 2-3 days before your endurance event. This timing, combined with a tapering of your training, allows your body to effectively store glycogen.

You should focus on low-fiber, easily digestible carbohydrates like white rice, pasta, and bread during the final 48 hours. This minimizes the risk of bloating and other digestive issues on race day.

Yes, a short-term weight gain of 1-2kg is common and expected. This is because for every gram of glycogen stored, your body also stores about 3 grams of water. This extra water helps with hydration and is a sign of a successful load.

Carb loading is generally not necessary for races shorter than 90 minutes. A balanced diet with adequate carbohydrates is sufficient for 5K or 10K events.

The night before, have a carbohydrate-rich dinner that is moderate in protein and low in fat and fiber. Eat on the earlier side to allow for digestion and avoid going to bed feeling overly stuffed.

Yes, sports drinks, energy gels, and chews are excellent for supplementing your carbohydrate intake, especially if you struggle to consume enough solid food. They provide easily absorbed carbs and help with hydration.