What To Eat Before a Marathon: The Exact Timing, Foods, and Portions That Work

The best pre-marathon fueling strategy for energy and performance

Last Updated: Mar 4, 2026 5:05 pm

Whitney Heins

Whitney Heins

Whitney Heins is a contributing editor; a VDOT-O2 Certified Running Coach, Proud Mother Runner

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Updated by Katelyn Tocci

Katelyn Tocci

Katelyn Tocci is our Head Coach and Training Editor; 100-mile ultrarunner, RRCA + UESCA Certified Running Coach

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

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.

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.

To get the best insights, we spoke with NYC-based licensed dietitian Amy Stephens, to break down everything you need to know about pre-marathon fueling—from the importance of breakfast timing and carb loading to race-day meal planning, foods to avoid, and even whether your pace, body size, and weather conditions should influence what you eat.

Plus, we’ll share a sample marathon morning meal plan to help you start your race fueled and ready to go.

Why Your Pre-Race Meal Could Make Or Break Your Marathon

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 gels or a sports drink 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.

“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 and 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 founder.

“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.”

Race-Day Breakfast Timing: How Early Should You Eat Before the Start?

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, then have 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.

Carb Loading Is More Than Just A Pasta Dinner—Here’s How To Do It Right

Carb loading requires a bit of thought; there’s more to it than a pre-race pasta feast the night before. It’s the strategic increase in carbohydrate intake before a marathon, specifically to boost glycogen stores in the muscles and liver.

When done right, carb loading helps prevent us from hitting the dreaded wall or “bonking” during a marathon by ensuring a sustained supply of carbohydrates, staving off fatigue at the end of 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 days before the marathon, gradually increasing carb intake while reducing fat and fiber intake. 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.

Your Night-Before-the-Race Dinner Game Plan

The perfect night-before meal should consist mainly of simple, easy-to-digest carbohydrates like pasta, white rice, potatoes, or bread to top off your glycogen stores.

Add a small portion of lean protein such as grilled chicken, tofu, or eggs—but only if you’re used to it—to help keep you satisfied without overloading your digestive system.

Avoid heavy sauces, spicy foods, and too much fat, which can interfere with sleep or cause GI distress on race morning. Think of this meal as your final tune-up: familiar, comforting, and focused on fueling, not indulging.

It’s essential to moderate fiber intake to avoid digestive issues during the race and stay adequately hydrated.

Stick to familiar foods that agree with your stomach, and aim to eat your well-balanced pre-marathon dinner 2–3 hours before bed to allow for proper digestion. That way, you’ll wake up feeling fueled, rested, and ready to run.

How To Avoid Race-Day Stomach Issues With Smart Fueling

To avoid GI distress 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 remains in the stomach can cause 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 on race morning, have a carbohydrate snack the night before so your glycogen stores are topped off.

What Foods You Should Avoid Before A Marathon

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

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

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

Eat simple carbs (for energy) with a little bit of protein (for tissue repair).¹

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. “Choose 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 guide)

A long-term nutrition plan would have you eating a variety of meals rich in 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 on 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 about 100 grams of carbohydrate and some protein.

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

Should I Eat More If I Am A Bigger Runner?

The exact equation is: 1 hour before a big race, 1 gram of carbohydrate per kilogram of 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 kilograms.)

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.

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.²

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

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