What to Eat Before a Marathon: When, What, And How Much To Eat

Carb-loading, expert tips for a strong start on race day

Figuring out what to eat before a marathon could make or break your race.


Because if you eat something your body is still digesting, you could wreck your stomach, have GI issues, and steal much-needed fuel away from your body. 

But, on the flip side, you could also supply your body with the fuel it needs to go 26.2 miles, especially when it’s running low on glycogen stores that last 10k. 

So, it’s a delicate balance: eat enough to fuel yourself.

But don’t eat too much that your tummy is still working hard when you hit the start line. 

We spoke with NYC-based licensed dietitian Amy Stephens, who works with elite runners, to find out:

So, let’s get started!

What To Eat Before a Marathon 1

Why Is Breakfast Before The Marathon So Important?

Eating the right breakfast in the morning before your marathon can help you go that extra mile—or, more specifically, that extra 6.2 miles

Most seasoned marathon runners know the race doesn’t really begin until the last 10k.

That’s when our bodies start to run out of fuel and essentially run on guts.

But what you eat can keep you from bonking (which is when your body runs out of energy to keep going):

Think of the meal before the race as fuel for your last 10k. The longer you can preserve those muscle and liver glycogen stores during the race, the more fuel is left in the tank for the last 6.2 miles,” explains Stephens.

Why? Our bodies can only store about 300 grams of glycogen, which can keep us running for about 1 1/2 hours. 

After that, we typically see runners hit the wall or bonk, which is when they run out of glucose.

You can take in GUs or Gatorade at that time, but it will take 15 min to a half-hour for your body to convert the food into usable energy for your muscles, says Stephens. 

What To Eat Before a Marathon 2

“The goal of race fueling is to eat enough to preserve those precious glycogen stores and use them up at a slower rate. Your pre-race meal will delay the use of your muscle glycogen. Many people who end up bonking didn’t take in enough fuel early on with a good breakfast or fueling at in the first half,” explains Stephens

Hence, that pre-race meal could be the difference between a PR or a DNF.

Think of your fuel stores as a bucket that’s leaking as you run your marathon,” says Thomas Watson, Marathon Handbook coach and editor.

Your job is to ensure the bucket is nice and full at the start line and is topped up regularly throughout the run such that the bucket never runs empty.”

“That’s why what to eat before a marathon is essential – you’re looking to fill up that bucket as effectively as possible!”

What To Eat Before a Marathon 3

When Should I Eat Before A Marathon?

You want to ensure you eat at least two hours before the race, says Stephens. 

Ideally, you eat your breakfast 3-4 hours before the marathon and then a snack an hour before.

“At the Chicago marathon, (American female marathon record holder) Deena Kastor would wake up at 4 am, eat a bowl of oatmeal and go back to sleep. (Then eat a snack an hour before).

We want those carbs to be digested and in our bloodstream at the time of the race,” shares Stephens.

What Are The Best Carb Loading Foods To Consume In The Days Leading Up To A Marathon?

Carb loading requires a bit of thought, there’s more to it than a pre-race pasta feast the night before.

Carb loading is the strategic increase of carbohydrate intake before a marathon, specifically to boost glycogen stores in muscles and the liver.

When done right, carb loading helps to prevent us hitting the dreaded wall or “bonking” during a marathon by ensuring a sustained supply of carbohydrates staving off the dreaded fatigue at the end or a race.

Carbohydrates also play a crucial part in adequate hydration, with every gram of stored glycogen accompanied by four grams of water. This hydration aspect is crucial for optimal race day performance.

Gradually increase carbohydrate intake in the days leading up to the race, replacing fat and fiber in meals with complex carbohydrates like rice, legumes, and potatoes.

If you want to get your marathon nutrition right, timing matters.

Start carb loading 3-4 days before the marathon, gradually increasing carb intake while reducing fat and fiber consumption. For half marathons, follow a similar protocol, aiming for 70 percent of calories from carbs in the days leading up to the race.

Check out our complete guide to carb loading!

What Is The Best Meal To Eat The Night Before A Marathon?

The perfect night-before meal should consist of a balanced mix of complex carbohydrates, such as pasta or quinoa, lean proteins like chicken or tofu for muscle support, and healthy fats, including avocado for sustained energy.

It’s essential to moderate fiber intake to avoid digestive issues during the race and stay adequately hydrated without turning your bedtime into a water break.

Stick to familiar foods that agree with your stomach.

Consume your well-balanced pre-marathon dinner 2-3 hours before bedtime to allow for proper digestion, ensuring you wake up ready to tackle the course with a well-fueled body.

How Do You Avoid Tummy Troubles When Running A Marathon?

To avoid tummy troubles during the marathon, focus on when and what you eat. 

“Your body can fully digest a meal in about two hours,” Stephens explains. “Focus on timing your foods so they are fully digested, and the energy is available when you start the race.”

Stomachaches usually come from eating too close to the start, so you’re running and trying to digest food at the same time.

The working muscles divert blood away from the gut when we start running, and whatever is left in the stomach can cause some GI issues.  

The goal of your breakfast is to maximize the amount of carbs your body can use without causing GI upset:  

  • Eating breakfast more than two hours before running a marathon will help you avoid stomach issues during the race.
  • Avoid high-fat and high-fiber foods because they can delay stomach emptying and cause gastrointestinal distress. 
  • Don’t eat a new food. If you want to try a new food, try it BEFORE race day. 
  • Also, don’t eat too much; otherwise, your body may still be digesting by the time you start running. 
  • If you have a hard time eating race morning, have a carbohydrate snack the night before so your glycogen stores are topped off.
What To Eat Before a Marathon 4

What Foods To Avoid Before A Marathon?

It’s good to have a nutritional plan before your marathon, particularly if it is your first marathon. When considering what to eat before a marathon, you want to stick with simple carbs and a bit of protein the morning of the marathon.

This gives your body what it needs to work hard and store energy. 

Avoid foods that are hard to digest.

This includes high-fiber foods that can make you gassy and bloated. “Running stimulates the GI tract, and fiber can exacerbate this problem,” explains Stephens.

Avoid high-fat foods and protein, which slow digestion and release energy more slowly. So, do not eat beans, lentils, or high-fiber cereals before your marathon. As always, there is room for individual preferences here; if you love a bean burrito before setting off, enjoy it!

“The longer a food sticks around in your gut, the more likely it will cause diarrhea, bloating, or gas,” says Stephens.

That is definitely NOT something runners want!

What To Eat Before a Marathon 5

What To Eat Before A Marathon: What’s Your Marathon Breakfast?

Simple and familiar is the name of the game the morning of your marathon.

Eat simple carbs (for energy) with a little bit of protein (for tissue repair).1Macnaughton, L. S., Wardle, S. L., Witard, O. C., McGlory, C., Hamilton, D. L., Jeromson, S., Lawrence, C. E., Wallis, G. A., & Tipton, K. D. (2016). The response of muscle protein synthesis following whole-body resistance exercise is greater following 40 g than 20 g of ingested whey protein. Physiological Reports4(15), e12893. https://doi.org/10.14814/phy2.12893

The exact ratio of macronutrients you should aim for is 4:1, 4 grams of carbohydrate for 1 gram of protein. But an estimate is fine! 

“Whether you are trying to BQ or just finish the race, you want foods to digest and convert into usable energy quickly,” says Stephens. “Chose low-residue carbs such as white rice, bread, bagels, energy bars, or low-fiber cereals.

(See a sample meal plan at the end of this post)

How Much Food Should I Eat On The Morning Of A Marathon?

A long-term nutrition plan would have you consuming a variety of meals full of veggies, healthy fats, and whole grains. Foods that are rich in nutrients, such as quinoa, sweet potatoes, and nut butter. But not on race day.

On race day, the focus is maintaining your energy levels via easy-to-digest carbohydrates until you reach the finish line.

More food is not necessarily better because too much food can take longer to digest and lead to diarrhea or stomach cramps, warns Stephens. 

Aim for something with about 100 grams of carbohydrate intake and some protein.

Save the more adventurous meals for the next day; you’ll have earned whatever you want to eat by then! 

What To Eat Before a Marathon 6

Should I Eat More If I Am A Bigger Runner?

The exact equation is 1 hour before a big race, 1 gram carbohydrate per kilogram of your body weight from food and liquids, explains Stephens. 

Thus, the earlier you eat, the more you can eat. And, the more you weigh, the more you eat. (You can divide weight in pounds by 2.2 to find kilogram.)

  • Two hours/2 grams of carbs per kilogram of weight
  • Three hours/3 grams of carbs per kilogram of weight
  • Four hours/4 grams of carbs per kilogram of weight

Use this information as you are training to see what your gut can handle when planning what to eat before a marathon. Some people digest foods faster or slower, adds Stephens. 

Should I Eat Something Different Depending On The Weather?

No matter the weather, stick with mostly carbs and a little bit of protein.

However, if it is going to be extra hot or cold (roughly warmer than 60 degrees Fahrenheit), hydrate more and add salt to your breakfast.

“This will help maintain electrolyte balance,” Stephens adds, noting that many runners in the 2021 Chicago Marathon had a difficult time racing in the second half due to dehydration. 

If it is going to be cooler than 30 degrees Fahrenheit, you still need to hydrate with water or a sports drink.

What To Eat Before a Marathon 7

Does My Marathon Race Pace Affect What I Should Eat?

Slower runners should aim to get up earlier before their race to eat more and allow time to digest their food.

This is because slower runners, with a less intense marathon pace, require even more carbs.

“The longer you run, the more energy your body needs to fuel the run and your other bodily functions such as breathing, digestion, neurological system, etc.,” explains Stephens.

Can I Drink Coffee The Morning Of My Marathon?

If you are used to coffee in the morning, then, by all means, drink your coffee!

“Coffee is definitely a performance enhancer,” says Stephens. Studies show caffeine gives runners pep in their step.2Higgins, S., Straight, C. R., & Lewis, R. D. (2016). The Effects of Preexercise Caffeinated Coffee Ingestion on Endurance Performance: An Evidence-Based Review. International Journal of Sport Nutrition and Exercise Metabolism26(3), 221–239. https://doi.org/10.1123/ijsnem.2015-0147

‌Stephens recommends 200 mg one hour before a race.

“Be sure to test this before race day if you’re not a coffee drinker. See how your body feels with caffeine,” warns Amy. 

Some people get GI distress with coffee, or it makes them need to use the bathroom a lot. Some people’s hearts also race with caffeine, which is not something you need the morning of the marathon. 

You can also try chews or gels with caffeine, which can also give a performance boost. 

Related: Should You Drink Coffee Before Running?

What To Eat Before a Marathon 8

Sample Marathon Morning Meal Plan

Here is a meal plan for what to eat on the morning of a marathon:

2-4 hours before the race starts:

  • 100 grams carb + protein
  • Bagel with peanut butter, banana, honey
  • Bowl of oatmeal, banana, peanut butter
  • Bowl of rice, nuts, banana
  • Granola bar, banana, toast
  • + 20 oz fluids

1 hour before the race starts:

  • Fruit
  • Dried fruit
  • Honey stinger wafer
  • + 10 oz fluids

15 min before the race starts:

  • GU gel
A plate of food with the words marathon training meal plans in the foreground.

Check out our free-to-download Marathon Training Meal Plans for four weeks of meal planning ideas during your training and carb-loading period!


Photo of author
Whitney Heins is the founder of The Mother Runners and a VDOT-O2 certified running coach. She lives in Knoxville, TN with her two crazy, beautiful kids, pups, and husband. She is currently training to qualify for the US Olympic Trials marathon.

1 thought on “What to Eat Before a Marathon: When, What, And How Much To Eat”

Leave a Comment

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