Fueling For a Marathon 101

Do you have a long run fueling strategy in place? Fueling for a marathon involves looking at many factors, which we will discuss in this post. 

female vegan ultra runner running on trail

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From staying adequately hydrated, to training your gut, to taking in enough fuel, these are some of the logistics that marathon runners need to consider for fueling during a marathon.

Let’s break each of them down.


It is always a good practice to start out adequately hydrated before a long run or race. Hydration for runners is of utmost importance and should be practiced continuously.

Increasing your fluid intake in the days leading up to the race, the night before, and the morning of is going to be good practice to reach adequate fluid status.

Forming a hydration plan for athletes will depend on your sweat rate and electrolytes lost in sweat. 

Hydration Before A Marathon

  • 2-3 hours before activity drink 20 oz. water or sports drink
  • 10-20 minutes before activity drink 10 oz. water or sports drink

Hydration Tips During Exercise

  • Begin exercise in an adequately hydrated state
  • Drink before you are thirsty
  • Drink a couple sips or gulps (approx. 4-8 oz. water or sports drink) every 15-20 minutes
  • Train yourself to drink during exercise if this is new to you
  • Sports drink will also provide carbohydrates and electrolytes (more on that below).

Hydration Tips After Exercise

  • Continue to drink after exercise on a regular basis
  • Aim to drink 16-24 oz. water or sports drink for every pound of body weight lost during exercise. The best way to estimate this is to weigh yourself naked before and after runs.
  • Protein shakes and smoothies can be a hydrating and good recovery drink after running
  • Consume salty snacks or foods – see more on what you should eat after a run
  • Notice if you have white residue spots on your clothes or skin from sweat; this means you are a ‘salty sweater’ and may require more electrolytes
marathon runner running towards water cup


Electrolytes, such as sodium, potassium, magnesium, and chloride, also play a key role in maintaining proper hydration.

Electrolytes are especially important if the weather is hot and/or humid and/or if you are a heavy sweater or a salty sweater.

Many runners will preload with electrolytes before running.

If you see or feel salt on your body or clothes after exercise, this can be an indication you are a salty sweater.

Electrolyte needs are very individualized but a good starting point is to consume 500 to 1000mg of sodium per hour during exercise.

Salty sweaters may do well with The Right Stuff, Drip Drop or salt tabs to get enough sodium. Adding salt to foods is also a great way to increase sodium intake to meet higher needs.

Soups, broths, salted nuts and nut butters, dairy, breads, crackers, and pretzels can be great to incorporate in your overall diet to help improve sodium intake.

Learn how to make your own electrolyte drink here.

electrolyte drink with lemon and lime


Half marathon nutrition and fueling for a marathon actually starts long before the marathon.

There are benefits of carb loading for runners 2-3 days in advance of the race.

Eating before a long run or race (with a breakfast for marathon runners) helps to provide extra FUEL for the muscles and the brain.

The main focus of this snack or meal should be CARBOHYDRATES such as bread, pasta, oats, potatoes, fruit, etc.

Pasta can be one of the best foods for carb loading before a competition.

A pre-workout meal before a long run or race may include:

  • two slices of peanut butter toast
  • half of a bagel with low fat cream cheese
  • a glass (roughly 8 oz.) of low-fat milk and a banana

This is a good combination of high carb, moderate protein, and a small amount of fat. Here’s a post on how many carbs should runners eat?

More recommendations here for what to eat the night before a long run

Again, you’ll want to experiment during training for your long run fueling strategy and see what works best for you.

In general, a low carb diet for runner isn’t going to help with performance, though it can be helpful for teaching the body to use more fat for longer distances. 

Fueling before a workout is especially important if the workout is going to last more than one hour or if the workout is high intensity and you are trying to perform your best.

Sports Drinks

Sports drinks are another option for fueling that include carbohydrates and help with hydration. 

Gatorade, powerade, Skratch Labs, Tailwind Nutrition and UCan are some options. 

Ucan fueling
Click here to order

Tailwind vs. Skratch

We get a lot of questions about Skratch vs. Tailwind comparing these two nutrition products so we thought they deserved their own heading.

There are lots of sports products out there such as gels, chews, and sports beverages that contain an ideal amount of carbohydrates (for fuel) as well as provide some electrolytes (such as sodium and potassium).

Other things to consider include texture, taste, flavor, caffeine amount, and portability (how will you carry it?).

Here’s a breakdown of some of the best chews for running and the best gels for the marathon to help you determine which may work best for you. 

Tailwind is a popular option. Their endurance fuel option mixes with water and provides calories and electrolytes. It comes available in four non-caffeinated flavors and four caffeinated flavors.

It is vegan and gluten free., so great for a vegan ultramarathoner or marathoner.

  • One scoop provides 25g of carbohydrates and 310mg of sodium.
  • It is recommended to mix this with 20-24 oz. of water.
  • Based on fueling and hydration recommendations, you may need 1-2 scoops per hour of racing.

Skratch is another popular option. Their sport hydration drink mix mixes with water and provides calories and electrolytes.

It is flavored with real fruit so has less sugar than other fueling products. It comes in seven different flavors, including one caffeinated flavor (matcha).

  • One scoop provides 21g of carbs and 380mg of sodium.
  • Compared to Tailwind, that’s a little less carbs (fuel) and a little more sodium per scoop.
  • You will likely need at least 2 scoops per hour of racing for optimal fueling using Skratch.
  • They also have a hyper hydration mix that has really high sodium (1720mg) for extreme conditions and is not to be used if you have high blood pressure or have been advised to limit your salt intake.
  • Their superfuel drink mix is another option but again, not for everyone. It contains 100g of carbs and 400mg of sodium per serving.

Knowing where your caffeine comes from is important and knowing the affects it can have on you are important.

This post talks about the difference between pre workout vs coffee for running.

What to Eat During a Marathon

When considering what to eat during a marathon, remember that the best fuel during a marathon is 100% what works for you.

You have to consider what to eat as well as when and how often to eat (or drink) as well.

What to eat while running a marathon is so individual. However, some (mostly carbohydrate) options that people eat include:

Fueling during a marathon means giving your body adequate carbohydrates through and through.

The general recommendation is to consume 30-60g of carbohydrates per hour (some people need more, especially if fueling for an ultra-marathon) after the first hour of exercise.

This means you’ll want to begin fueling with carbohydrates about 45-60 minutes into your race. Fuel early and often! This will help decrease your marathon recovery time.

Finally Understand How to Fuel For Running!
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intuitive eating ebook

You may not feel you need the fuel that early on, but it is better to start fueling early rather than waiting until it’s too late.

You then risk cramming everything down or hitting the wall, which is why your long run fueling strategy should be practiced many times before race day.

An important part of taking in carbohydrates during the race is to take them with water, and take them consistently. Don’t overload them all at once.

group of runners running a race

What if You Have Stomach Issues During a Marathon?

If you suffer from runners gut symptoms, you’ll want to evaluate your nutrition plan pre marathon and stay away from unfamiliar foods before running.

If you are traveling for a race, make sure to bring some of your usual pre-workout fueling options as well as plan ahead and search the area you will be staying in to find some options for pre-race fueling.

If you are truly unable to eat anything the morning of a marathon, I would recommend drinking something with carbs such as 100% fruit juice or sports drink.

Additionally, consider increasing your carb intake the day and night before as  your body can store some amounts of carbs from fuel, it just can’t store enough to get  you through an entire marathon.

Many people rate UCan as a great product for sensitive stomachs. They have gels now so they may be great running gels for sensitive stomachs.

They also have an energy powder you can mix in your water and/or have beforehand.

Ucan fueling
Click here to order

Everyone’s body is unique and can handle different types and amounts of food before a workout.

In general, before a long run or race, you’ll want to decrease your fiber intake such as beans, high-fiber fruits and vegetables, whole grains, seeds, etc.

These foods can cause GI issues such as bloating, gas, constipation, and/or diarrhea.

You’ll also want to decrease your fat intake such as cheese, ice cream, fatty meat, avocado, nuts, and seeds as these foods take longer for the stomach to digest and therefore may cause GI issues.

woman runner hunched over on knees while running

Remember that you can train your gut to take in carbs during long runs and it does deserve time and patience as you practice.

This is an important step to having your gut able to tolerate different carbohydrate foods.

Other Considerations for Fueling a Marathon

These are some other factors to think about for your marathon race day and fuel during a marathon.

Firstly, you want to make sure you are eating enough throughout your training cycle – carbs, protein and fat. BCAAs and creatine are not necessary supplements if one is getting enough protein in the diet.

More on BCAAs vs creatine here. 

  1. Bringing your own food and hydration – When preparing for a marathon, you’ll likely have experimented with and found a hydration and fueling strategy that works for you. Therefore, you may want to continue this on race day by bringing and carrying your own hydration and fuel during the race. This requires you to think about what gear and products you will need to make this happen and make sure to test those out during training as well.
  2. What’s provided on the course – You may also want to look at what will be provided on the course. If it’s products you know and use, you can plan to use those on race day. However, I still recommend bringing and carrying your own as you never know if they may run out of products before you get to the fueling stations or if they won’t have your particular flavor available, etc. It’s always best to be over prepared!
  3. Weather conditions – You’ll also want to watch and consider what the weather conditions will be like on race day, especially if you are traveling for the race, as the weather may be quite different from what you’re used to. Weather will impact your clothing choices but also your hydration and electrolyte plan. Hotter or more humid weather will likely require you to take in more fluids and/or electrolytes before and during the race to avoid dehydration or muscle cramping.
  4. Travel – You’ll want to have a plan if you are traveling for the race. What will you bring with you in regards to hydration and fueling? What will you get at the airport or once you arrive to your location? I recommend planning ahead so you have your go-to fueling options available for the night before and the morning of the race.

And remember, practice your fueling and hydration plan during training! Don’t try anything new on race day.

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 Sports Nutrition: A Practice Manual for Professionals, 5th ed. (2012)

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