Should I Eat a Lot of Carbs Before a Race?

October 20, 2025 •

4 min read

According to a 2022 review in Sports Medicine, strategic carbohydrate loading can improve an athlete's performance in endurance events lasting more than 90 minutes by up to 3%. But should I eat a lot of carbs before a race, and how does this process actually work? The answer depends on the race length and how you approach this fueling strategy.

Quick Summary

Strategic carb loading can maximize glycogen stores for endurance events, but isn't necessary for shorter races. The process involves increasing carbohydrate intake for 1-3 days beforehand while consuming low-fiber, easily digestible foods. Practice your fueling plan during training to find what works best for your body.

Key Points

Endurance Events Only: Carb loading is primarily beneficial for races longer than 90 minutes; shorter races do not require this strategy.
Strategic, Not Excessive: Carb loading is a calculated process of increasing carb intake over 1-3 days, not an excuse to binge eat.
Focus on Low-Fiber Carbs: In the days leading up to the race, prioritize easily digestible, low-fiber carbohydrates like white rice, pasta, and bagels to avoid stomach upset.
Practice During Training: Always test your fueling strategy during long training runs to ensure your body tolerates the foods and timing.
Timing is Crucial: The final meal should be 2-4 hours before the race, with a smaller, simple carb top-up 15-30 minutes before the start.
Hydration is Key: Remember to increase fluid intake during carb loading, as glycogen stores extra water, which helps with race-day hydration.

The Science of Carb Loading

Your body's primary fuel source for high-intensity, long-duration exercise is glycogen, which is stored in your muscles and liver. During an endurance race, like a marathon, your body taps into these reserves for energy. A typical, well-fed person can store enough glycogen for about 90 to 120 minutes of intense activity. Once these stores are depleted, you can experience a dramatic drop in energy, a phenomenon known as "hitting the wall.".

Carb loading is a nutritional strategy used to super-saturate your body's glycogen tanks, extending the time before your reserves run dry. This isn't about gorging on a huge bowl of pasta the night before, but rather a strategic, multi-day process of increasing your carbohydrate intake while simultaneously tapering your training volume. The reduced training load prevents your body from using up the extra carbs, ensuring they get converted and stored as glycogen.

Modern Carb-Loading Protocols

Older, more extreme methods involved a glycogen-depletion phase, where athletes would significantly restrict carbs for several days before the loading phase. However, modern research shows this is unnecessary and can be stressful on the body. Effective current protocols focus on simply increasing carb intake for 1-3 days leading up to the race.

What to Eat and When: A Practical Guide

2 to 3 Days Before the Race

This is when you shift your nutritional focus. The goal is to increase the percentage of your total calories from carbohydrates, not to simply overeat. During this time, your training volume should be significantly reduced as part of your taper. Focus on easily digestible, low-fiber, high-glycemic carbohydrates to maximize glycogen storage and avoid gastrointestinal issues on race day. Foods high in fiber, fat, and protein should be minimized as they slow down digestion.

Recommended foods: White rice, pasta, bagels, white bread, oatmeal, pancakes, potatoes, and bananas.
Foods to limit: High-fiber cereals, whole grains, beans, and excessive amounts of raw vegetables.
Liquid carbs: Include sports drinks, fruit juices, or sweetened tea to help meet your high carb target without feeling overly full.

The Night Before the Race

Your evening meal should be relatively small, carb-heavy, and eaten on the early side to allow for proper digestion. Stick to simple, familiar foods you've tested during your training runs. Avoid anything new, spicy, or overly fatty that could cause an upset stomach.

Examples: Plain pasta with a simple tomato sauce, baked potato with minimal toppings, or white rice with grilled chicken.

Race Morning

Your pre-race breakfast serves as a final top-up of your glycogen stores, especially your liver glycogen, which gets used overnight. The timing is crucial to allow for digestion and prevent hypoglycemia.

Time it right: Aim to eat 2-4 hours before your race starts.
Example meals: Bagel with nut butter and a banana, oatmeal with honey, or toast with jam.
Just before the gun: A quick hit of simple carbs like a gel, chews, or a small handful of gummy bears 15-30 minutes before the race can provide a last-minute energy boost.

The Role of Timing: Race Duration Matters

Carb loading isn't a one-size-fits-all strategy. The importance and execution of this nutritional plan depend heavily on the length of your race.


Race Duration	Is Carb Loading Needed?	Carb Loading Strategy	Race Morning Fueling	In-Race Fueling
Short (<60-90 min)	No. The body's normal glycogen stores are sufficient.	Not necessary. Focus on a normal, balanced diet.	A small, easily digestible, carb-rich snack or meal 1-2 hours prior is sufficient.	Unnecessary.
Medium (90 min - 2.5 hr)	Recommended to maximize performance.	Follow a 1-2 day modern carb-loading protocol.	Standard pre-race breakfast 2-4 hours before, with 1-4g of carbs/kg of body weight.	30-60g of carbs per hour.
Long (Marathon & Ultra)	Essential to delay fatigue and avoid "the wall".	Follow a 2-3 day modern carb-loading protocol.	Standard pre-race breakfast, up to 4g of carbs/kg of body weight.	60-90g of carbs per hour.

Practicing Your Fueling Plan

Just like your physical training, your nutrition strategy needs practice. Use your longest training runs as a dress rehearsal for your race-day fueling. Experiment with different food combinations and timings to discover what works best for your body without causing GI distress. This practice is vital for building gut tolerance, ensuring you can digest and absorb the necessary fuel during your race.

Conclusion: Strategic Fueling for Peak Performance

So, should I eat a lot of carbs before a race? The answer for endurance events over 90 minutes is a definitive yes, but with a crucial caveat: it must be done strategically. Carb loading is not an excuse to binge but a deliberate process of increasing glycogen stores. By focusing on low-fiber, easily digestible carbs in the days leading up to the race and practicing your fueling plan during training, you can ensure your energy reserves are topped up and you're ready for your best performance. For shorter races, a balanced diet and a light pre-race meal are all you need. Ultimately, effective fueling removes one of the biggest variables from your race day, giving you the confidence to focus on your performance. You can find more detailed advice on sports nutrition from reputable sources like the International Society of Sports Nutrition.

Common Carb-Loading Mistakes to Avoid

Overeating: Carb loading is not a green light to stuff yourself with massive portions, which can lead to bloating and discomfort.
Waiting too late: Starting the process only the night before is ineffective. Glycogen supercompensation takes 1-3 days.
Ignoring fiber and fat: Eating too much fiber, fat, or protein close to the race can slow digestion and cause stomach upset.
Trying new foods: Race day is not the time for experimentation. Stick to what you know works for your body.
Forgetting hydration: Glycogen stores with water. You need to stay adequately hydrated during the carb-loading period.

Frequently Asked Questions

Carb loading is a nutritional strategy used by endurance athletes to maximize the amount of glycogen, or stored carbohydrates, in their muscles and liver in the days leading up to a race.

Modern research suggests starting your carb-loading protocol 1 to 3 days before your event, while also tapering your training volume to allow your body to store the extra glycogen.

Focus on easily digestible, low-fiber carbohydrates, such as white rice, pasta, white bread, oatmeal, potatoes, and bananas. Sports drinks and fruit juices can also be used to supplement solid food intake.

No, carb loading is not necessary for shorter races like a 5K or 10K. A standard, balanced pre-race meal 1-2 hours before the event is sufficient to top off your energy stores.

Opt for a small, carb-heavy meal that includes familiar, low-fat, and low-fiber foods. Examples include plain pasta with marinara sauce or a baked potato.

You may experience a temporary weight gain of 2-4 pounds during carb loading. This is due to the extra water your body stores with glycogen, which is beneficial for hydration during the race.

Bloating is a common side effect, often caused by eating too much fiber or trying new foods. To minimize this, stick to familiar, simple carbohydrates and consume smaller meals and snacks throughout the day.