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

Photo of author
Written by

Aside from your marathon pace training, long runs, strength training sessions, and attempt at a good night’s sleep and a nutritious diet, daily fueling is as critical as all the pieces to your marathon puzzle. 

Maintaining a well-balanced, nutritious diet throughout your training, and before, during, and after your race, is the key to completing your 26.2 miles. 

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

More specifically, we will cover, 

  • Fuel For A Marathon: Day-To-Day Nutrition
  • Fuel For A Marathon: Pre-Race 
  • Fuel For A Marathon: During The Race 
  • Fuel For a Marathon: Post-Race 

Ready? Let’s jump in!

A runner holding a granola bar.

Fuel For A Marathon: Day-To-Day Nutrition

Throughout your training, you must ensure you take in enough calories to support your workouts and the wear and tear marathon training takes on your body. 

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 many calories, and the body needs to provide adequate energy sources to fulfill its demands. 

Although these numbers can vary depending on each athlete’s specific needs, a caloric breakdown for most endurance athletes is ideally 60% carbohydrates, 25% fat, and 15% protein. 

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

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 a healthy diet.

One hour prior to 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 at your best. 

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

After all your workouts, a protein-dense meal or shake is vital for recovery. If you run in the morning, an ideal breakfast consists of an omelet filled with delicious vegetables, cheese, and sliced turkey, or a protein smoothie with your favorite protein powder, milk, and fruit. 

Now, jumping into pre-race nutrition.

A person eating a fruit salad.

Fuel For A Marathon: Pre-Race


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 all of your meals and snacks, so they are more carb-based. 

If you usually eat string cheese and ham roll-ups for a protein-filled snack, replace it will an English muffin and jam, a bowl of cereal, or yogurt with your favorite granola. Accompany your fish and veggies for dinner with roasted sweet potato and fluffy couscous. 

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

This will hydrate you and sneak in a few extra carbs and electrolytes leading up to the marathon. 

A bowl of pasta.

Fuel For A Marathon: The Night Before

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 mostly all simple carbs. 

Simple carbs are easy to digest, while protein and fats stay in the system longer as they are more challenging to process. When talking about the night before a race, we want to ensure we are doing everything possible to avoid digestive distress. 

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

Tips for doing so include: 

  • Stick to what you know. Eat exactly what you have been eating the night before your long runs; no new foods! If this means you must bring a Tupperware full of your pasta, do so. You don’t want an unwanted surprise of gastrointestinal 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 avoid consuming 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.

Fuel For A Marathon: 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. 

Fuel For A Marathon: 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, use the following equation to calculate your carbohydrate fuel for a marathon. 

Weight in kilos = grams of carbohydrates consumed per hour

For example, if you weigh 70 kilos, you should consume 70 grams of carbohydrates per hour for sufficient fuel during the marathon. 

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

But what about hydration? 

To calculate your hydration needs, take a sweat test. 

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 sweat. 
  4. Weigh 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. 

People running a marathon.

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 4:30 marathon. 

  • Per hour, our runner will need to consume three gels containing 23-25 grams of carbohydrates each, adding up to about 14 gels (round up rather than down) throughout the race.
  • 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 gels just in case. The last thing you want is to bonk or hit the wall due to poor fueling. 

A runner drinking a protein shake after the marathon.

Fuel For a Marathon: Post-Race 

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 suggests 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 a lot 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. 

For some excellent ideas and recipes for everything we have mentioned, take a look at the following articles for meal and snack ideas: 

The 12 Best Pre-Workout Meals To Fuel Your Burn

17 Best Post-Workout Breakfast Options To Recover Well

Here’s 10 Awesome Protein Shake Recipes

A forkful of pancakes and syrup.
Photo of author
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!

Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.