Should I Eat a Lot of Carbs the Day Before a Race? The Smart Fueling Strategy

December 17, 2025 •

3 min read

According to sports dietitians, many endurance athletes fail to consume enough carbohydrates to properly replenish muscle glycogen stores, which can negatively impact performance. This often stems from misconceptions about proper fueling strategy, including a common belief that a massive pasta dinner the night before is the best approach.

Quick Summary

This guide explains the most effective method for carbohydrate loading, focusing on timing, food choices, and avoiding common pitfalls to maximize performance for endurance events.

Key Points

Timing is key: Start carb loading 36-48 hours before an endurance race, not just the night before.
Prioritize Low-Fiber Carbs: Stick to easily digestible, low-fiber carbs like white rice, pasta, and potatoes to avoid race-day stomach issues.
Hydrate Constantly: Increase fluid intake during the carb-loading period, as glycogen stores require water to be retained.
Moderate, Don't Binge: Control portion sizes and total calorie intake. Emphasize carbs while moderating fat and protein, rather than overeating everything.
Test During Training: Always test a race-day fueling plan during long training runs to know how the body reacts.
Consider Race Duration: Carb loading is most beneficial for endurance events over 90 minutes; it's less critical for shorter races.

The Science of Glycogen: Why Carbs are King

For any endurance event lasting longer than 90 minutes, carbohydrates are the primary fuel source for muscles. The body stores these carbohydrates in the muscles and liver in the form of glycogen. These glycogen stores function as the body's rechargeable battery pack. During intense, prolonged exercise, the body burns through this readily available energy. If these stores become depleted, a phenomenon known as "hitting the wall" occurs, where a sudden and dramatic drop in energy is experienced. Maximizing these stores before a big race is a critical component of a successful fueling strategy.

The Truth About Eating a Lot of Carbs the Day Before

The idea of a single, excessive carb-heavy meal right before a race is a widespread misconception. Strategic carbohydrate loading is important, but a single day of overeating can be detrimental. Consuming an unusually large amount of food, especially high-fiber or high-fat foods, in a short window can lead to gastrointestinal (GI) distress, including bloating, gas, and an upset stomach during the race. The optimal strategy involves a controlled, multi-day approach rather than a last-minute binge.

The Critical Timing: More Than Just the Day Before

Effective carb loading typically begins 36 to 48 hours before an event. It's a progressive strategy, not a cramming session. During this period, training volume should be decreased concurrently, a process known as tapering. Tapering ensures the body is not burning through glycogen stores while actively trying to top them off. In practice, this means increasing carbohydrate intake gradually, while decreasing fat and protein consumption to manage the total calorie load and avoid feeling overly full.

Quality Over Quantity: The Right Carbs for Race Day

Not all carbohydrates are created equal in the context of race fueling. While whole grains are beneficial for daily nutrition, the days leading up to a race require a more refined approach. High-fiber foods, like legumes, certain vegetables, and whole grains, can cause GI issues. Focusing on lower-fiber, easily digestible carbohydrate sources helps prevent stomach discomfort and ensures efficient absorption.

Best Foods for Carb Loading

White pasta
White rice
White bread or bagels
Potatoes (peeled)
Oats (lower fiber varieties or cooked well)
Fruit juices and sports drinks
Bananas
Pancakes with syrup

Foods to Avoid the Day Before a Race

High-fiber cereals and breads
Large salads and raw vegetables
Legumes and beans
Fried and fatty foods
Spicy foods
New or unfamiliar foods

High-Fiber vs. Low-Fiber Carbs for Pre-Race Nutrition


Feature	High-Fiber (Generally avoid pre-race)	Low-Fiber (Ideal for carb loading)
Digestion Speed	Slow digestion, can cause bloating and gas.	Fast digestion, less likely to cause discomfort.
Examples (Carbs)	Whole wheat bread, brown rice, quinoa, lentils, broccoli, leafy greens.	White bread, white rice, pasta, potatoes (peeled), crackers.
Examples (Fruits/Juices)	High-fiber fruits like apples, pears, and berries.	Juices, less ripe bananas.
Primary Goal	Provides sustained energy and digestive health for daily diet.	Rapidly fills glycogen stores for immediate race day use.

Hydration: The Often-Overlooked Partner to Carbs

One often-forgotten aspect of carb loading is hydration. For every gram of glycogen stored, the body stores approximately three grams of water. This means that as carbohydrate intake increases, fluid needs also rise significantly. Staying well-hydrated in the days leading up to a race supports glycogen storage and helps regulate body temperature during the event. Sip fluids consistently and aim for pale, straw-colored urine as a guide for adequate hydration. Over-hydrating to an extreme can also be harmful, so a steady, conscious effort is best.

The Final Conclusion: A Tactical Not a Gluttonous Approach

Instead of stressing over eating a massive amount of carbs on the day before a race, embrace a strategic, two-day carbohydrate loading plan. By gradually increasing carb intake while tapering training, and selecting easily digestible, low-fiber carb sources, it is possible to effectively top off glycogen reserves without risking digestive upset. The goal is to feel energized and light on race day, not heavy and bloated. Practicing this fueling method during longer training sessions is key to discovering what works best for the body. A thoughtful approach will help start the race with a full tank, ready to perform at the best.

Frequently Asked Questions

While a pasta meal is a classic pre-race option, eating a massive, excessive portion the night before can cause digestive upset and discomfort. A better strategy is to increase carb intake gradually over 36-48 hours and keep the final meal moderate.

Focus on low-fiber, easily digestible carbohydrates like white rice, pasta, bread, potatoes, and bananas. These are less likely to cause gastrointestinal issues during the race compared to high-fiber alternatives.

Yes, but in moderation. Carbohydrates should be emphasized by reducing fat and protein intake slightly to prevent overeating and to allow for more concentrated carb calories without adding excessive bulk.

Avoid high-fiber foods like whole grains and many raw vegetables, as well as high-fat, spicy, and unfamiliar foods, all of which can cause stomach problems during the event.

Carb loading is not necessary for races lasting less than 90 minutes, as the body's normal glycogen stores are typically sufficient. For shorter races, a balanced diet and proper hydration are key.

Feeling bloated is a common side effect of carb loading, as the body stores extra water along with the glycogen. This is normal and a sign fueling is on track, but sticking to low-fiber foods can help minimize the discomfort.

Yes, adequate hydration is essential. For every gram of glycogen stored, the body retains several grams of water, so increased fluid intake is necessary to support the process effectively.