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Running Nutrition: how to fuel During a Race

Updated: Aug 18, 2023

Woman holding running gels

I will never forget when I ran my first half-marathon.

I had such an enjoyable race and felt invincible, yet exhausted when I passed the finish line. However, soon after I began to feel pretty bad. I was extremely nauseated and couldn’t even eat at the post-race brunch celebration. I had no idea what was happening but assumed this was just a side effect and a normal part of running 13.1 miles.

Have you ever assumed something was normal as a runner, only to realize later it doesn’t have to be that way?

After mentioning my experience to other runners during group runs, I learned that this wasn’t normal and entirely preventable. From here, I began my journey to learn more about running nutrition. I’m passionate about helping others avoid the mistakes I made so they can experience more joy and success in their own running journey.

Ultimately, nutrition is one of the most important parts of training and racing.

I want to preface this by stating that I am NOT a registered dietician. I am a certified running coach with years of my own running experience as well as a bachelor’s degree in science. What I’m sharing with you are general guidelines when it comes to nutrition, specifically around running.

If you’re looking for a specific nutritional program, I would highly recommend finding a sports dietitian to work with. If you are looking for recommendations, please reach out and I'd be happy to share my favorites.

Importance of Fuel During a Race

Do you need fuel during every race?

NO. Generally, it’s important to fuel during a run/race if you’re running longer than 90 minutes. 90 minutes is about the time that the body’s glycogen stores can likely support the effort without additional fueling. I say generally because fueling during a race is very individualized. Ultimately, do what feels good for YOU.

Other than GI upset, not fueling during a race most commonly leads to what runners refer to as “bonking” or “hitting a wall”. Basically, your legs run out of energy and can feel like lead for the last several miles of a race.

Woman exhausted after running.

If you want to feel good during your race, finish strong and meet your desired pace, having a fueling strategy in place that you’ve tested out before race-day can help ensure you get there.

Fueling Guidelines

Now that we know it’s important to fuel during long runs, how do we know how often or how much?

This goes back to the individualized aspect. There are guidelines available for us to start with, but everyone will fuel differently in terms of what fuel they use and how often they fuel. It’s important to practice ahead of race day so that you know exactly what works best for you.

During runs, it’s advised that simple carbohydrates are used as fuel, as they are easily broken down for immediate use as energy. Several variables increase carbohydrate and caloric requirements including intensity of the run, heat/humidity, and altitude. If any of those pertain to your race, you’ll want to keep that in mind when making your fueling strategy.

Here’s the basic guideline: runners should aim to take in between .32 to .45 grams of carbohydrates per pound of body weight per hour. It sounds complicated but it’s not, even if you hate math!

Here’s an example: Runner is 140 lbs.
.32 to .45 x 140 lbs. = 45 to 63 grams of carbs per hour

Keep in mind, 1 GU gel is about 22 grams of carbs per gel. Therefore, in the above scenario, this athlete would want to start by trying 1 gel every 30 minutes (2 gels/hour) to reach the carbohydrate goal.

Ultimately, your tolerance of carbohydrate intake will end up determining how many carbs are consumed per hour. Do what feels good. If you find that taking a gel every 30 minutes causes GI distress, back off and try every 45 minutes. If you feel like you need more, adjust as needed.

Types of Fuel to Use During a Run

There are many options available to use as fuel during a race. Most products available contain different types of sugars, so it’s important to practice with different types of products to experiment with how your body will respond to the different types of fuels.

Most common race fuel types:

  • Typically, pretty small, gels are compact and easy to store during a race or a long run.

  • Gels vary in consistency from brand to brand, as well as what they are made of. You simply squirt the gel in your mouth while running (or take a walk break) and always follow with water. It’s important to always take a few sips of water to help it digest.

GU running gels.

Common brands include GU, HUMA, Maurten, Honey Stinger, and CLIF, among many others.

  • Exactly as they sound, chews provide carbohydrates in the form of a gummy-like candy.

  • Just like gels, there are several different brands where ingredients vary as well as types of sugars used.

Skratch brand running chews.

Common brands include GU, Skratch, Honey Stinger, and Jelly Belly Sports Beans, among many others.

  • If you have no desire to chew or shoot gel into your mouth during your run, rest assured there is another option! Drink mixes are available that you add to your water which adds carbohydrates to what you’re already drinking.

  • It’s important to note exactly how much is in each packet that you use so that you know if that’s enough to sustain you during your run.

Tailwind endurance running fuel.

Common brands include GU, Tailwind, and Skratch among many others.

You can stick with one method of fueling or combine all methods above to help you reach your carbohydrate goal. You can also try other ways such as traditional candy, dried fruit, etc. I once spoke to a runner who shared that her fueling strategy consisted of cooked sweet potatoes that she brought with her during her race!

Most importantly, anything you plan to use on race day, you should test out during training to ensure your body will respond in a way that feels good.

How to Prepare for Race Day

Runners' legs during a race

When preparing for race day, the first and most important thing to consider is will you be carrying your own fuel with you during your race OR will you stop at the aid stations and use the fuel provided? This will determine how you train during long runs.

I can’t stress this enough – NOTHING NEW ON RACE DAY! From shoes on your feet to what type of fuel you use, you will want to have tested it all.

If you’ll use the aid stations/bring nothing with you:

  • Find out ahead of time what type of fuel will be available and exactly how often. This information can typically be found on the race website. If not, email the contact for the race to inquire. Make sure to specifically ask what flavor and brand (for example, if they say GU gels will be available, you’ll want to know exactly which one).

  • Once you know what fuel will be provided during the race, purchase that exact product and flavor, and begin using it during your training runs.

  • If you feel great using that product, great! Continue training with it.

  • If you do not like that product (stomach upset, taste, texture, etc.) move on to the steps outlined below ⬇️

If you’ll bring your fuel with you:

  • If you aren’t already training with a certain product or aren’t sure what you’ll like, start practicing early in training.

  • Go to a local running store, if available, and stock up on different products and flavors to try during training.

  • Once you identify what you like and what makes you feel good, stock up on that product – making sure you have enough for race day.

  • Make sure you’ll have enough room to carry your nutrition products with you on race day. From leggings with pockets, to running belts, there are a ton of ways to keep everything on you.

Fueling on race day is important but it doesn’t have to be difficult.

Start practicing and trying products early in your training. If you’re in any running groups or have running friends, you’re sure to get everyone’s opinion on what fueling strategy and product is best. Simply put, there is no best. There’s only what works for you.

If you’re training for a big race and find that you’ve got lots of other questions outside of nutrition, my 1:1 Coaching program may be a good fit for you. Together we create a personalized training plan based on your goals, availability, and interests. With education and mindset work, you’ll feel confident in your plan and the why behind it as well as overcome motivation fluctuations so you can get out of your own way.

Woman running coach in KC shirt.

If you’re interested in learning more, schedule a free introductory call here where we will chat about your goals and how I can help you get there.

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