How to Fuel Up Before a Long Run

December 7, 2025 •

4 min read

Proper fueling can make or break your performance, with some studies showing that a 2% loss in body fluid can negatively impact endurance. Knowing how to fuel up before a long run is a critical skill for any serious runner aiming to perform at their best and prevent the dreaded wall. This preparation involves more than just a quick snack; it is a strategic approach to nutrition and hydration.

Quick Summary

This article details optimal nutritional strategies for runners preparing for a long run, including meal timing, ideal food and drink choices for sustained energy, and what to avoid to prevent gastrointestinal issues. It provides a comprehensive plan for fueling success.

Key Points

Timing is key: Eat a substantial, carb-focused meal 2–4 hours before a long run, or a small snack 30–60 minutes before for a quick energy boost.
Prioritize carbs: Focus on easily digestible carbohydrates like oatmeal, bananas, or white toast to top up your glycogen stores for sustained energy.
Hydrate strategically: Drink fluids consistently throughout the day and before your run. Include electrolytes for runs over 60 minutes, especially in warmer weather.
Know what to avoid: Steer clear of high-fiber, high-fat, spicy foods, and dairy products before a run to prevent digestive upset.
Practice makes perfect: Use your training runs to experiment with different foods and timings to find what works best for your body, ensuring you're ready for race day.
Train your gut: Gradually build up your tolerance for fuel intake during your long runs by introducing it in small, spaced-out increments.

Why Pre-Run Fueling Is Crucial

Proper nutrition before a long run is essential for optimizing performance and preventing fatigue. Your body's primary energy source during exercise is glycogen, which is stored in your muscles and liver. During a long run, these stores become depleted, a phenomenon known as "hitting the wall". By strategically fueling your body, you can top up your glycogen stores, maintain stable blood sugar levels, and ensure you have the energy needed to power through your run. The right nutrients also support hydration and help prevent stomach upset, which is common among runners.

Timing Is Everything: Your Pre-Run Meal Schedule

The timing of your pre-run meal is just as important as what you eat. Here’s a general timeline to follow, which should be practiced and perfected during your training sessions.

2–4 Hours Before the Run

This is the ideal window for consuming a substantial meal. The focus should be on easily digestible carbohydrates to maximize glycogen storage, with a moderate amount of lean protein and minimal fat and fiber. A balanced meal in this window gives your body ample time to digest the food and convert it into usable energy without causing stomach discomfort.

Example Meals:

Oatmeal with a banana and a tablespoon of nut butter
Two slices of toast with a thin layer of peanut butter and jam
A bagel with egg whites
Pasta with a light, non-creamy sauce and some lean chicken

30–60 Minutes Before the Run

If you have an early morning run or didn’t get a chance to eat a full meal earlier, a small, carb-focused snack is a good option. The goal here is a quick energy boost without weighing you down.

Example Snacks:

A banana
A handful of pretzels
A small energy gel or chews
A few dates or dried apricots

Comparison of Pre-Run Meal Components


Nutrient	Purpose for Runners	High-Fiber Foods (Avoid)	Low-Fiber/Easily Digestible Foods (Prefer)
Carbohydrates	Primary fuel source, replenishes glycogen.	Whole grain cereals, lentils, raw vegetables.	White bread, bananas, oatmeal, white rice, pasta.
Protein	Aids muscle repair; moderate amounts are fine.	High-fat meats, large servings of beans.	Egg whites, low-fat yogurt, lean chicken.
Fat	Provides energy, but can slow digestion.	Fried foods, heavy sauces, butter.	Small amounts from nut butter, avocado.
Fiber	Helps regulate digestion, but can cause GI distress.	Broccoli, beans, high-fiber cereals.	White toast, plain rice cakes, peeled fruit.

Hydration Is Your Secret Weapon

Beyond solid food, proper hydration is paramount for a long run. Your body loses fluids and electrolytes through sweat, and replacing them is crucial for performance and safety.

How to Hydrate:

Start Early: Begin hydrating throughout the day leading up to your run. Aim for a consistent intake rather than chugging water right before. Your urine should be a pale straw color.
Pre-Load: Drink 16–20 ounces of water or a sports drink 2–3 hours before your run.
Just Before: Have 6–8 ounces of fluid about 15 minutes before you start.
Electrolytes: For runs over 60 minutes, consider a sports drink containing electrolytes to replace lost sodium and potassium. This is especially important in warm or humid conditions or if you are a heavy sweater.

What to Absolutely Avoid Before a Long Run

To prevent mid-run issues like stomach cramps, indigestion, and the dreaded "runner's trots," it's critical to avoid certain foods.

Foods to Avoid:

High-Fiber Foods: These can stimulate your digestive system and cause a need for an urgent bathroom break.
Spicy Foods: Can cause heartburn and indigestion.
High-Fat Foods: Digest slowly and can lead to a heavy, bloated feeling.
Excessive Protein: While some protein is okay, too much can also slow digestion.
Dairy Products: Can cause stomach upset in some runners.
Carbonated Drinks: The gas can lead to bloating and discomfort.
New Foods: Never experiment with a new food or drink on race day or before a key long run. Always test your fueling strategy during training.

Training Your Gut

Your digestive system can be trained to tolerate fuel intake during a run, just like your muscles can be trained for endurance. This is a process of gradually introducing fuel during your training runs to find out what works best for you and your stomach.

Start Small: Begin by consuming a small amount of a sports drink or energy chew during a shorter long run (e.g., 60-90 minutes).
Increase Gradually: As your gut adapts, slowly increase the amount of carbohydrates you consume per hour, aiming for 30–60 grams per hour for runs over 90 minutes.
Space It Out: Take smaller amounts of fuel more frequently (e.g., every 20–30 minutes) rather than large amounts all at once to prevent stomach issues.

Conclusion

Mastering your pre-run fueling is a critical component of successful endurance running. By timing your meals correctly, prioritizing easily digestible carbohydrates, staying properly hydrated with water and electrolytes, and avoiding foods that cause digestive issues, you can significantly enhance your performance and comfort. Experiment during your training runs to discover the personalized strategy that best fuels your body. Remember, your pre-run preparation sets the stage for success, ensuring you have the energy and endurance to conquer any distance. For more in-depth information on the physiology of endurance sports nutrition, you can consult authoritative resources such as the International Society of Sports Nutrition guidelines.

Reference: The International Society of Sports Nutrition (ISSN) is a reliable source for evidence-based sports nutrition guidelines, providing detailed information on timing, hydration, and macronutrient intake for various athletic endeavors. International Society of Sports Nutrition (ISSN)

Frequently Asked Questions

The night before a long run, focus on a balanced meal rich in complex carbohydrates and moderate in protein, with low fiber and fat. Examples include pasta with a lean chicken breast or a baked potato with salmon and vegetables.

Yes, even a small, easily digestible snack like a banana or a few dates will top up your liver glycogen stores and provide the energy you need for a long run, even if you run first thing in the morning.

A simple way to check your hydration is by the color of your urine. If it is a pale straw color, you are likely well-hydrated. If it is dark yellow, you need to drink more fluids.

Stomach issues can be caused by eating too close to a run, consuming too much fiber or fat, or drinking too much at once. Experiment with timing and food choices during training, and try spacing out your fuel intake.

For shorter, easy runs (under 60 minutes), running fasted might be fine if you had a good meal the night before. However, for long runs, consuming some carbohydrates before or during is highly recommended to maintain energy levels and performance.

For runs over an hour, a sports drink offers both carbohydrates for energy and electrolytes to replace what is lost through sweat, helping to prevent cramping and fatigue. Plain water is sufficient for shorter runs.

Aim for about 5–10 ounces of water or a sports drink every 15–20 minutes during a long run. Individual needs vary based on factors like weather and sweat rate.