How To Fuel For A Marathon: What To Eat Before, During, + After Your Race

In addition to your pace training, long runs, strength training, and attempts at a good night’s sleep, a well-balanced nutrition plan and marathon fueling strategy are just as critical as all the pieces to your marathon (or half marathon) puzzle. 

Maintaining a well-rounded, nutritious diet throughout your training process and dialing in your marathon nutrition before, during, and after your training runs and race are the keys to completing your 26.2 miles successfully. 

In this guide, we will explain how to fuel for a marathon, what to eat during your training, and what to eat before, during, and after your marathon to have an excellent race and get you to that finish line.

A runner holding a granola bar.

How Do You Fuel For A Marathon?

Whether it’s your first marathon or your tenth, marathon runners must ensure they take in enough calories to support their workouts and the wear and tear marathon training takes on their bodies. 

Running in a caloric deficit will only be helpful if you are trying to lose weight, but those trying to maintain their weight and muscle mass while training for their marathon must eat enough calories to sustain the workouts.

Day-to-day, eat a nutritious, well-rounded diet containing all three macronutrients: carbohydrates, protein, and fat.

More often than not, a runner’s diet tends to be more carbohydrate-based as running burns a boatload of calories, and the body needs to provide adequate energy sources to fuel its demands. 

Although these numbers can vary1Schröder, S., Fischer, A., Vock, C., Böhme, M., Schmelzer, C., Döpner, M., Hülsmann, O., & Döring, F. (2008). Nutrition Concepts for Elite Distance Runners Based on Macronutrient and Energy Expenditure. Journal of Athletic Training43(5), 489–504. depending on each athlete’s specific dietary needs, a caloric breakdown for most endurance athletes is ideally 60% carbohydrates, 25% fat, and 15% protein. 

Focus primarily on minimally processed food sources, including whole grains, vegetables, fruits, lean proteins, low-fat dairy products, and healthy fats full of the essential vitamins and minerals necessary to maintain healthy nutrition.

Blocks that spell out balanced diet and healthy food surrounding it.

What Should You Eat During Marathon Training?

At least one hour before all of your workouts, eat a prerun snack made up of simple carbohydrates to top off your glycogen stores and provide the necessary energy to perform. 

Toast or an English muffin and jam, oatmeal, or a granola bar are all great choices to get you going. 

After all your workouts, ideally within the first half an hour, consume a protein-dense meal or shake for recovery. It is important what you choose to consume also contains carbohydrates.

If you run in the morning, an ideal breakfast could consist of an omelet filled with delicious vegetables, cheese, and sliced turkey with a side of whole wheat toast or a protein smoothie with your favorite protein powder, milk, nut butter, or fruit. 

Now, jumping into pre-race nutrition.

A person eating a fruit salad.

What Is The Best Way To Fuel For A Marathon?

Pre-Race Carb-Loading 

Begin to carb load three days before your marathon.

This doesn’t mean we stuff ourselves with cookies and cake (even if we are tempted to) and overdo it.

Still, we increase our general carbohydrate intake by replacing some protein and fat in our diets with carbohydrates during these three days before the marathon. 

Arrange your meals and snacks so they are more carb-based than usual. 

If you usually eat string cheese and ham roll-ups for a protein-filled snack, replace it with an English muffin and jam, a bowl of cereal, or yogurt with your favorite granola and berries. 

Accompany your fish and veggies for dinner with roasted sweet potato and fluffy couscous. 

As you carb load, ensure you are also hydrating, drinking enough water throughout the day, and perhaps adding a 12-ounce bottle of your favorite sports drink to your daily intake for an extra kick of carbs and electrolytes.

A bowl of pasta.

How Do You Fuel The Day Before the Marathon?

Now that you’ve carb-loaded the past few days by replacing some protein and fats with carbs, you can completely knock out those other macronutrients the night before a race and stick to simple carbs. 

Simple carbs are easy on the digestive system, as opposed to protein and fats that stay in the system longer as they are more challenging to digest and process. 

When discussing the night before a race, we want to avoid at all costs any foods that may cause digestive distress. For each runner, this will depend on sensitivities to certain foods or perhaps be restricted due to a specific diet being followed.

A bowl of pasta, rice, couscous, or even a protein-light sandwich are all viable options for a pre-race high carb dinner.

For your pre-run dinner, keep these tips in mind:

  • Stick to what you know. Eat exactly what you have been eating the night before your long runs during your marathon training; no new foods! If this means you must bring a Tupperware full of pasta, do so. You don’t want an unwanted surprise of GI distress the night before or, worse, the day of the race. 
  • Don’t overeat. Again, we want to avoid tummy trouble, so eat enough, but not until you are stuffed. If you get hungry later, eat a simple carb-rich snack to top off your glycogen stores and stop your stomach from rumbling before bed. 
  • Eat simple carbs. Avoiding complex carbs is essential to consume mininmal fiber the night before a race. Unplanned bathroom breaks are no fun during a marathon and will surely put a damper on your plans. 
A stack of toast and strawberry jelly.

Fueling The Morning Of

Enjoy a simple carb-filled pre-race breakfast on your marathon morning, ideally 3 hours before your race. It’s important to leave this 3-hour window so your system can process the food adequately and you are not running on a full stomach. 

Again, this meal should be something you are accustomed to eating and have practiced the morning of your long runs. 

Examples include toast with honey, pancakes with maple syrup, waffles, or a bagel and jam or peanut butter. 

Fueling During The Race 

During your race, you want to consume sufficient carbohydrates and electrolyte-filled fluid from start to finish. 

If you’ve yet to determine how much you should consume during your marathon, you can use the following equation to estimate your carbohydrate fuel for optimal energy levels. 

Everyone is different, so this is just a broad estimate based on weight. You may need more or less depending on other factors, such as intensity level and how well your system can handle fuel sources while competing.

Weight in kilos = grams of carbohydrates consumed per hour

For example, if you weigh 70 kilos, you should consume about 70 grams of carbohydrates per hour for sufficient fuel on race day. 

A person getting handed a bottle of water in a marathon.

But what about hydration? 

To calculate your hydration needs, take a sweat test to calculate your sweat rate. 

Sweat Test

Perform your sweat test in similar conditions to your marathon, if possible. This way, you will get an accurate calculation of just how much fluid loss you will experience throughout the marathon.

  1. Weigh yourself right before your run (with no clothes or shoes on!)
  2. Run for one hour at race pace without ingesting or expelling any fluid; in other words: no drinking or peeing!
  3. When you complete your run, remove your shoes and clothes, wring out your hair, and wipe off any excess sweatWeigh yourself again, with no clothes or shoes on. 

If using pounds, subtract your post-run weight from your prerun weight and convert this number to ounces. 

Example: If you weighed 154 pounds before your run and 153 pounds afterward, you lost 1 lb of fluid or 16 ounces. 

Using kilograms, subtract your post-run weight from your prerun weight and convert the number to milliliters. 

Example: If you weighed 70 kilograms before your run and 69.5 kilos afterward, you lost 500 milliliters of fluid.

After calculating your fluid loss, ideally, you would like to consume at least 80% of that amount per hour to keep well-hydrated throughout the race. 

Let’s look at a race-strategy option for our 70-kilo runner, who plans to run a 4 hour marathon marathon. 

  • Per hour, our runner will need to consume about three gels containing 23-25 grams of carbohydrates each, adding up to about 10 gels throughout the race, beginning 30-35 minutes in.
  • Per hour our runner will need to consume at least 400 ml of water or a calorie-free electrolyte drink, just about a full standard-sized handheld water bottle.

Suppose the runner would prefer only to consume liquid calories and hydrate simultaneously. In that case, they may do so by choosing a sports drink product that contains the number of carbohydrates per 400-500-milliliter bottle to add up to roughly 70 grams per hour.

Remember, races don’t always turn out exactly how we want them to, so take along a couple of extra caffeinated gels or some chews just in case. The last thing you want is to bonk or hit the wall due to poor fueling. 

Also, keep in mind that if you plan on only using the aid stations for fueling instead of carrying bottles or hydration packs, it may be more difficult to gauge the quantity of fluids you consume. Do your best to keep track to ensure you are getting enough.

A runner drinking a protein shake after the marathon.

Post-Race Fueling

Even though the last thing many want to do after a race is eat, as we are packed to the brim with Gatorade and energy gels, post-race fueling plays a big part in your recovery.

Drinking a recovery shake of protein and carbohydrates within 20 minutes to half an hour of your race finish is ideal. 

Research suggests2C, K., T, H., J, S., B, C., C, W., R, K., D, K., T, Z., H, L., J, L., Jl, I., & J, A. (2008, October 3). International Society of Sports Nutrition Position Stand: Nutrient Timing. Journal of the International Society of Sports Nutrition. that your body needs between 0.5 and 0.7 grams of carbs and between 0.14 and 0.23 grams of protein per pound of body weight after a run.

Also, ensure you are rehydrating with electrolytes, as you will have sweat during the race. No matter how well you hydrate during the marathon, your body will most likely be depleted. 

Later on, when your system has recovered and your stomach starts rumbling, you can enjoy that post-marathon meal you’ve been looking forward to! Make sure it includes nice portions of carbohydrates and protein to boost your body on its road to recovery. 

Working with a dietitian or nutritionist and running coach is ideal for putting together your specific fueling strategy and eating plan to meet your needs.

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  • 1
    Schröder, S., Fischer, A., Vock, C., Böhme, M., Schmelzer, C., Döpner, M., Hülsmann, O., & Döring, F. (2008). Nutrition Concepts for Elite Distance Runners Based on Macronutrient and Energy Expenditure. Journal of Athletic Training43(5), 489–504.
  • 2
    C, K., T, H., J, S., B, C., C, W., R, K., D, K., T, Z., H, L., J, L., Jl, I., & J, A. (2008, October 3). International Society of Sports Nutrition Position Stand: Nutrient Timing. Journal of the International Society of Sports Nutrition.
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Katelyn is an experienced ultra-marathoner and outdoor enthusiast with a passion for the trails. In the running community, she is known for her ear-to-ear smile, even under the toughest racing conditions. She is a UESCA-certified running coach and loves sharing her knowledge and experience to help people reach their goals and become the best runners they can be. Her biggest passion is to motivate others to hit the trails or road alongside her, have a blast, and run for fun!

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