How much carb loading for one day?

December 17, 2025 •

3 min read

According to sports nutrition experts, a one-day carb loading protocol requires a significantly higher intake of carbohydrates than a multi-day approach. This intensive strategy is designed to rapidly maximize your muscle glycogen stores, which is critical for peak performance in endurance events lasting over 90 minutes.

Quick Summary

This guide outlines the precise carbohydrate intake required for effective one-day carb loading, detailing the grams per kilogram athletes need to consume. It covers best practices, food choices, and hydration to maximize glycogen stores and improve endurance performance.

Key Points

Calculate grams per kilogram: Aim for 10-12 grams of carbohydrates per kilogram of body weight during a one-day carb load.
Choose low-fiber carbs: Opt for easily digestible, low-fiber foods like white rice, pasta, and potatoes to avoid stomach upset and maximize intake.
Spread intake out: Consume your carbohydrates across 5-6 smaller meals and snacks throughout the day, rather than in one or two large sittings.
Hydrate adequately: Increase your fluid intake, especially with electrolytes, as glycogen stores water and proper hydration is crucial for the process.
Practice first: Always test your one-day carb loading strategy during a long training run to understand your body's reaction before a major event.
Reduce exercise: Pair your high-carb intake with a significant decrease in exercise volume to allow your body to store the energy effectively.
Don't forget protein and fat: While focusing on carbs, include moderate amounts of lean protein and healthy fats to support muscle repair and prevent excess calories from fat.

How To Determine Your One-Day Carb Loading Needs

For a one-day or 24-36 hour carb-loading period, sports dietitians and nutrition experts recommend consuming 10-12 grams of carbohydrates per kilogram of body weight. This is a more aggressive approach than the 2-3 day protocols, which typically suggest 7-8 grams per kilogram, because you have less time to accumulate the necessary glycogen stores. This high intake is paired with a significant reduction in training, known as tapering, to ensure the ingested carbohydrates are stored as glycogen rather than used for energy.

To calculate your personal target, simply multiply your weight in kilograms by 10 to 12. For example, a 70 kg (154 lb) athlete would aim for 700-840 grams of carbohydrates throughout the day leading up to their race. This is a substantial amount, so spreading the intake across 5-6 smaller meals and snacks is key to avoiding gastrointestinal distress.

Prioritizing High-Carb, Low-Fiber Foods

During a one-day carb load, food selection is crucial. You should prioritize easily digestible, high-carbohydrate, and low-fiber options to maximize intake without causing stomach discomfort. Bulky, high-fiber foods fill you up too quickly, making it difficult to hit your carb targets.

White starches: White rice, white pasta, white bread, and peeled potatoes are excellent choices.
Simple sugars: Fruit juice, sports drinks, honey, jam, and some candies can help meet your goals without adding unnecessary bulk.
Low-fiber fruits: Bananas, applesauce, and oranges are good, easily digestible options.
Energy bars and gels: Specially formulated sports nutrition products are a compact and convenient way to boost carbohydrate intake.

Strategic Meal and Snack Timing

To manage the high volume of food, distribute your carb intake evenly throughout the day. Waiting until the night before the race to have one giant "pasta party" is an outdated strategy that often leads to bloating and discomfort. Instead, focus on a structured eating plan with balanced meals and frequent, carb-rich snacks.

Breakfast: A substantial, high-carb, low-fiber meal within a couple of hours of waking up. Example: White toast with jam, a large banana, and fruit juice.
Mid-morning snack: Pretzels or a low-fat energy bar.
Lunch: White pasta with a simple marinara sauce and a lean protein source like grilled chicken.
Mid-afternoon snack: Sports drink and a handful of gummy bears.
Dinner: A final high-carb meal, eaten early enough to allow for proper digestion before bed.
Evening snack: A bowl of low-fiber cereal with low-fat milk.

Comparison of One-Day vs. Multi-Day Carb Loading


Feature	One-Day Carb Loading (24-36 hours)	Multi-Day Carb Loading (2-3 days)
Carb Intake (g/kg/day)	10-12g	7-10g
Carb Source Focus	Higher proportion of simple sugars and low-fiber foods	Can include more complex carbs and slightly more fiber initially
Training Taper	Full rest or very light activity in the 24-36 hours	Gradual reduction in training volume and intensity over several days
Potential GI Issues	Higher risk if not practiced and food choices are poor	Lower risk due to less aggressive daily intake
Feasibility	More challenging to consume the high volume of carbs	Easier to manage intake over a longer period
Weight Gain	Temporary weight gain (1-2kg) from glycogen and water is expected	Similar temporary weight gain

The Importance of Hydration and Electrolytes

Hydration is a critical partner to your carb-loading strategy. Glycogen is stored with water in the muscles, so increasing your fluid intake is essential to maximize storage and prevent dehydration. For every extra gram of carbohydrate stored, your body stores approximately 3 grams of water. Incorporate fluids with your meals and snacks, and consider adding electrolytes, especially sodium, to assist with water retention. This will help you feel optimally fueled and hydrated on race day.

Conclusion

One-day carb loading is an effective, modern strategy for endurance athletes who need to maximize muscle glycogen stores in a compressed timeframe. By consuming 10-12 grams of carbohydrates per kilogram of body weight, prioritizing easily digestible low-fiber foods, and maintaining excellent hydration, you can ensure your energy tanks are topped off for peak performance in events lasting over 90 minutes. However, this is an advanced strategy, and practicing it during training is vital to understand your body's response and avoid stomach issues. For shorter events, a regular balanced diet is sufficient, but for marathons and other long-distance races, this targeted approach can provide the energy boost you need to succeed.

Frequently Asked Questions

Yes, modern research and practice show that a 24-36 hour carb loading protocol consuming 10-12g of carbs per kg of body weight is adequate for maximizing glycogen stores for endurance events. Depletion phases or longer loading periods are no longer considered necessary.

Focus on high-carbohydrate, low-fiber foods that are easy to digest, such as white pasta, rice, white bread, fruit juice, sports drinks, and bananas. Minimizing fiber helps prevent gastrointestinal discomfort.

Yes, a temporary weight gain of 1-2 kg is normal and expected during carb loading. This weight comes from the extra water stored alongside glycogen in your muscles and is a sign your body is effectively storing fuel for your race.

Consuming too much fiber can lead to feelings of fullness, bloating, and potential stomach upset during your race. It is best to choose lower-fiber alternatives to help your stomach cope with the high volume of carbs.

Eat your final high-carb meal early the evening before your race to allow for proper digestion. Avoid a heavy meal right before bed to prevent a restless night.

No, carb loading is generally only necessary for high-intensity endurance events lasting longer than 90 minutes. For shorter races, a normal, balanced diet is sufficient.

Yes, proper hydration is extremely important. Glycogen stores are dependent on water, so increasing your fluid intake, including electrolytes, helps maximize energy storage and prevent dehydration.

On race morning, consume 1-4g of carbs per kg of body weight, 1-4 hours before the race, to top off liver glycogen stores. Good options include a bagel with jam, a banana, or a sports drink.