How Soon Should I Eat Carbs Before a Run?

October 18, 2025 •

4 min read

According to sports nutrition guidelines, proper carbohydrate timing can significantly enhance endurance performance and prevent fatigue. The optimal window for consuming carbs before a run depends on the intensity and duration of your workout, with different types of carbohydrates serving different purposes. This guide explains how soon you should eat carbs to maximize your energy and minimize stomach issues.

Quick Summary

Optimal carbohydrate timing before a run varies depending on the workout's intensity and duration. For sustained energy, consume complex carbs a few hours prior. For quick fuel, eat simple carbs closer to the run. Adjusting your timing helps prevent GI discomfort and boosts performance.

Key Points

Long Runs (90+ min): Eat complex carbs 2-4 hours prior for sustained energy.
Short Runs (under 60 min): Consume simple carbs 30-60 minutes before for a quick fuel boost.
Practice: Experiment with your fueling strategy during training runs to avoid race-day surprises.
Avoid GI Distress: Stick to low-fiber, low-fat foods in the hours before a run to prevent stomach issues.
Carb Loading: For endurance events, a 24-48 hour mini-carb load can maximize muscle glycogen stores.
Listen to Your Body: Individual tolerance varies, so pay close attention to how different foods and timings affect your performance and digestion.

Timing Your Carbohydrates Based on Run Intensity

Proper fueling is a crucial component of any runner's training plan, and the timing of your carbohydrate intake is just as important as the quantity. A runner's needs differ significantly based on whether they're heading out for a short, easy jog or tackling a long-distance race. The key is understanding how the body utilizes different types of carbs and timing your intake to provide a steady supply of energy without upsetting your stomach.

For Runs Over 90 Minutes: The Importance of a Pre-Race Meal

For longer, more intense runs, such as a marathon or a long-distance training session, your body relies heavily on muscle glycogen for fuel. Eating a balanced meal a few hours beforehand helps to top off these stores. A general recommendation is to eat 2 to 4 hours before the run. This gives your body ample time to digest the food and convert the carbs into stored energy. Aim for a meal that is primarily composed of complex carbohydrates, with moderate protein and low fiber and fat, to ensure easy digestion. Examples include oatmeal with banana, or a bagel with a thin layer of nut butter.

Example meal timing for a long run:

4 hours before: A bowl of oatmeal with banana and honey.
2 hours before: A plain bagel with a small amount of jam.
30 minutes before: A sports gel or a few sports chews.

For Shorter, High-Intensity Runs: Quick Fuel is Key

If your run is less than 60 minutes and is a shorter, more intense session like an interval workout, you don't need a heavy meal. In this case, your body requires quick-acting fuel to power your muscles immediately. Simple carbohydrates are your best option here because they are rapidly digested and absorbed into the bloodstream. A light snack 30 to 60 minutes before the run can provide the boost you need without causing digestive issues.

Example snack timing for a short, intense run:

45 minutes before: A small banana or a handful of pretzels.
30 minutes before: A sports gel or a few energy chews.

The Role of Complex vs. Simple Carbs

Not all carbohydrates are created equal, and understanding the difference is key to a successful fueling strategy.

Complex Carbohydrates

These are found in whole grains, legumes, and starchy vegetables. They are broken down slowly by the body, providing a sustained release of energy over a longer period. Complex carbs are best consumed several hours before a long run. For example, brown rice, whole-wheat pasta, and sweet potatoes are great choices for a pre-race meal.

Simple Carbohydrates

These are sugars that provide a rapid, but short-lived, energy boost. They are quickly digested, making them ideal for topping up energy stores right before a run or during prolonged exercise. Simple carb sources include bananas, energy gels, sports drinks, and pretzels.


Feature	Complex Carbs	Simple Carbs
Digestion Speed	Slow	Fast
Energy Release	Sustained and steady	Rapid burst, then crash
Best For	Meals 2+ hours before long runs	Snacks 30-60 minutes before short runs, and during long runs
Examples	Oatmeal, whole-wheat bread, brown rice	Bananas, energy gels, sports drinks, pretzels
Fiber Content	High	Low
Key Benefit	Long-lasting fuel	Quick energy top-up

Practicing Your Fuelling Strategy

Your training runs are the perfect time to test your nutrition strategy. Just as you train your legs, you can train your gut to handle fuel during exercise. Experiment with different foods and timing to see what works best for your body. You don't want to try a new fuel source or timing on race day, as this can lead to unexpected gastrointestinal distress.

The Day Before: A Mini-Carb Load

For longer events, a mini-carb load 24 to 48 hours beforehand can be beneficial. This involves slightly increasing your carbohydrate intake while reducing fat and fiber. This strategy helps ensure your glycogen stores are fully saturated before the event begins, preventing you from 'hitting the wall'. White pasta and white rice are good choices here due to their lower fiber content, which reduces the risk of stomach upset on race day.

Conclusion

The ideal timing for eating carbs before a run is not a one-size-fits-all answer, but rather a spectrum determined by your workout's length and intensity. For long-distance efforts, prioritize complex carbs 2-4 hours beforehand to provide sustained energy. For shorter, high-intensity runs, a smaller, simple carb snack 30-60 minutes out will provide a quick and easily digestible boost. Above all, use your training to experiment and find the fueling strategy that works best for your body. This personalized approach to carbohydrate timing will help you maximize performance and avoid unpleasant stomach issues on the road.

Authoritative Reference

For more in-depth information, the American College of Sports Medicine provides comprehensive guidelines on nutrition and athletic performance: Nutrition and Athletic Performance

Frequently Asked Questions

Simple carbohydrates are digested quickly, providing a rapid energy boost suitable for immediate pre-run fuel or during exercise. Complex carbohydrates digest more slowly, offering sustained energy over a longer period, making them ideal for pre-race meals several hours out.

For easy, short runs under an hour, running on an empty stomach might be fine if you're accustomed to it, as your body's glycogen stores are usually sufficient. For longer or more intense runs, however, fueling with a small, simple carb snack is recommended to top off liver glycogen stores and prevent early fatigue.

Eating too close to a run can lead to gastrointestinal (GI) issues such as cramping, bloating, and nausea, especially with larger meals or those high in fiber, fat, and protein. The body is diverting blood flow to digestion instead of your muscles, which can also hinder performance.

Good pre-run carb options include simple carbs like bananas, sports drinks, and energy gels for quick energy, and complex carbs like oatmeal, white rice, or bagels for sustained energy before a longer effort.

For long-distance races, increasing your carb intake for 24-48 hours beforehand (mini-carb loading) helps to maximize muscle glycogen stores. Focus on low-fiber, high-carb options like white rice and pasta to minimize GI distress.

During runs over 90 minutes, aiming for 30 to 60 grams of carbohydrates per hour helps to maintain intensity and prevent hitting 'the wall'. This can be consumed through sports gels, chews, or sports drinks.

This depends on timing and personal tolerance. For a meal 2+ hours out, solid food is fine. However, closer to the run (30-60 minutes), liquid carbs like sports drinks or easily digestible snacks are often better tolerated and provide quicker fuel without stomach upset.