Fueling Your Performance: A Guide on What Kind of Carbs to Eat Before a Race?

October 25, 2025 •

4 min read

Research indicates that optimal glycogen stores can fuel endurance athletes for up to two hours during a race. Mastering what kind of carbs to eat before a race is essential for topping off these reserves, delaying fatigue, and ensuring you have the energy needed to cross the finish line strong.

Quick Summary

This guide covers the strategic use of different carbohydrate types and timing your intake to optimize energy stores for peak race day performance, minimizing digestive issues.

Key Points

Carb-load 1-2 days out: Maximize glycogen stores for endurance events by consuming complex, low-fiber carbs like white pasta, rice, and oats.
Race morning meal (2-4 hours before): Eat a moderately-sized, easily digestible meal rich in carbs and low in fiber, such as a bagel with jam.
Last-minute boost (30-60 minutes before): Use simple sugars like a banana or energy gel for a quick energy spike right before the start.
Prioritize low-fiber carbs pre-race: Avoid high-fiber foods, like whole grains and legumes, in the final 48 hours to prevent potential GI distress.
Practice your fueling strategy: Never experiment with new foods or gels on race day; test everything during training runs to see what works best for your body.

The Strategic Science of Pre-Race Fueling

For endurance athletes, carbohydrates are the body's preferred and most efficient fuel source. Proper pre-race fueling is a multi-step process that involves strategically consuming different types of carbohydrates at specific times to maximize your glycogen stores—the stored form of glucose in your muscles and liver. Ignoring this crucial aspect of preparation can lead to fatigue, also known as 'hitting the wall,' and significantly impact performance. Your nutrition plan should be practiced during training to ensure your body responds well, preventing any unpleasant race day surprises.

The Power of Carb-Loading (24-48 Hours Pre-Race)

For endurance events lasting longer than 90 minutes, such as a half or full marathon, carb-loading is key to topping off glycogen tanks. This involves shifting your diet to be predominantly carbohydrate-focused, while slightly reducing protein and fat intake. During this phase, the focus should be on complex carbohydrates. These carbs are made of longer chains of sugar molecules, which the body breaks down slowly, providing a sustained release of energy.

White Pasta: Easy to digest and a traditional favorite for endurance athletes. A simple marinara sauce is best to keep fat and fiber low.
White Rice: Similar to white pasta, white rice is lower in fiber than its brown counterpart, making it easier on the stomach closer to race day.
Oatmeal: A fantastic source of complex carbs, oats can be paired with bananas or honey. Use regular or quick oats to reduce fiber content.
Potatoes: Both white potatoes and sweet potatoes are excellent sources of complex carbs and provide valuable nutrients. Prepare them baked or roasted with minimal fat.

It is vital to avoid high-fiber foods like legumes, raw vegetables, and whole-grain breads during the final 48 hours to minimize the risk of gastrointestinal (GI) distress during your race. The goal is to build up fuel reserves smoothly and without bloating.

Race Morning: The Final Fill-Up (2-4 Hours Before)

On race morning, the purpose is to top off your liver glycogen stores, which deplete overnight. This meal should be moderate in size, high in easily digestible carbs, and low in fiber and fat. Stick to foods you've tested and know your body tolerates well during training.

Bagel with Jam or Honey: A classic, simple carb meal that's easy to digest. Pair it with a small amount of nut butter for some protein if you're eating more than two hours out.
Oatmeal with a Banana: Provides a steady release of energy from the oats and a quick boost from the banana. Using a quick-cooking variety can be easier to digest.
White Toast with Honey: Simple, fast-digesting, and effective for topping up energy levels without upsetting your stomach.

The Last Minute Boost (30-60 Minutes Before)

In the final hour before the race begins, your body needs a shot of quick-acting energy. At this point, simple carbohydrates are your friend. These are sugars that are rapidly absorbed into the bloodstream for immediate fuel.

Energy Gels or Chews: Designed specifically for athletes, these provide a concentrated, easily consumed dose of simple sugars.
Banana: A quick, natural source of simple carbs and potassium, which helps prevent cramping.
Pretzels: Easily digestible, salty, and a good source of simple carbs and sodium.
Sports Drink: Provides both simple carbs and electrolytes to aid with hydration.

Choosing Your Carb Type: Complex vs. Simple

Knowing when to use each type of carbohydrate is the key to a successful fueling strategy. The slower-digesting complex carbs are for long-term glycogen storage, while the faster-digesting simple carbs are for immediate energy needs.


Feature	Complex Carbohydrates	Simple Carbohydrates
Digestion Speed	Slow, providing sustained energy.	Fast, providing a quick energy boost.
Timing for Intake	Best for carb-loading (24-48 hours before) and post-race recovery.	Ideal immediately before and during a race for quick fuel.
Fiber Content	Higher fiber content in whole-grain options; opt for refined versions closer to race day.	Generally low in fiber, reducing risk of GI issues.
Example Foods	Pasta, oatmeal, potatoes, rice, quinoa.	Bananas, energy gels, sports drinks, dried fruit, honey.

Minimizing Gastrointestinal Distress

Runner's trots and other GI issues can be a serious setback on race day. To mitigate this risk, focus on low-fiber, low-fat options in the final 24-48 hours. Fat and fiber slow digestion and can cause discomfort during intense exercise. Practice your race day fueling strategy during training to identify which foods work best for your digestive system. Never introduce a new food, gel, or drink on race day itself.

The Importance of Hydration

Proper hydration is intrinsically linked to effective carbohydrate utilization. Your body stores water along with glycogen, so drinking plenty of fluids is crucial for a successful carb-load. Continue to hydrate steadily throughout the race, especially during longer events, using a mix of water and sports drinks to replenish both fluids and electrolytes lost through sweat.

Conclusion: Perfecting Your Race Day Plate

Choosing what kind of carbs to eat before a race depends entirely on the timing. By strategically separating your carbohydrate intake into a slower, glycogen-building phase (using complex, low-fiber carbs) and a faster, immediate-energy phase (using simple carbs), you can optimize your fueling strategy. Remember that practice is paramount; what works for one athlete may not work for another. Test your plan during your long training runs to ensure you show up to the start line feeling energized, not weighed down.

For more detailed guidance on endurance nutrition, consult a reputable resource like the Mayo Clinic's guide on fueling your run for good nutrition: Fueling your run with good nutrition - Mayo Clinic Health System.

Frequently Asked Questions

No, carb-loading is primarily beneficial for endurance events lasting over 90 minutes, such as half or full marathons. For shorter races, a normal, balanced diet is typically sufficient.

Complex carbs provide a slow, sustained release of energy and are ideal for building glycogen stores over days. Simple carbs offer a quick, immediate energy boost and are best for consuming right before or during a race.

Both white pasta and white rice are excellent for carb-loading. They are easily digestible and provide the necessary carbohydrates. Choose whichever you prefer and have practiced with during training.

About 30-60 minutes before your race, a small snack of simple carbohydrates is best for a quick energy boost. Good options include a banana, an energy gel, or a few crackers or pretzels.

High fiber can slow down digestion and potentially cause gastrointestinal distress, bloating, and stomach cramps during a race, which can negatively impact your performance. Low-fiber, refined carbs are preferred.

Yes, a small amount of peanut butter on a bagel or toast can be part of a pre-race meal consumed 2-4 hours beforehand. However, avoid high-fat and high-protein foods too close to the race start.

Yes, staying well-hydrated is crucial during carb-loading. Your body stores water along with glycogen, so drinking plenty of fluids is necessary to maximize energy storage.