Ultramarathon Nutrition Guide: What to eat before, during, and after an Ultra

Our running coach and ultra guru shares her nutrition secrets.

As ultra runners, you soon learn that our ultramarathon nutrition and fuelling needs to be a priority.

Running such long distances requires us to fuel sufficiently to keep up with our constant calorie burning both during actual training runs and also in our overall diet to maintain a healthy body weight and energy levels. 

Personally, as a competitive ultrarunner, it’s tough for me to consume all of the calories I need on a day-to-day basis, especially during a run or race. Still, I know that to perform at my absolute best, I need to make an effort to do so.

Rhe nutrition strategy for ultra-endurance events is all about taking in glucose to prevent glycogen depletion (and the dreaded bonking!) with your carbohydrate intake while also meeting caloric needs without causing gastrointestinal issues…it’s not easy!

Ultramarathon nutrition

How to Fuel as an Ultra Runner

Each of us has different nutritional needs, making it essential to learn what we each specifically require.

I strongly suggest going to a sports nutrition professional who is experienced in half marathon or marathon nutrition (if not ultras!) and is ideally an endurance athlete themselves. 

Sports nutritionists with experience with distance running nutrition will be able to give you the best advice possible to ultimately perform at your maximum capacity. They will be able to determine your metabolic rate and thus your macronutrients and caloric needs and whether you need supplements.

That said, I am a UESCA-Certified Ultramarathon Coach, and have been running ultras myself for years, so I have a great educational and practical background in fueling for ultras.

On a day-to-day basis, I genuinely believe in a well-balanced diet, full of protein and vegetables and our all-important carbohydrates. I use fats sparingly and try to make them the good ones, but it would be a lie to say that I follow a keto or high-fat diet.

But, I do love some “junk food” as part of my diet.

As ultra runners we have earned those cookies! Let’s just try to consume everything in moderation and follow our nutritional plan as closely as possible.

I don’t know about you, but my favorite time for fueling is the famous carb-loading before a race; and boy do we need it!

Ultramarathon nutrition

Pre-Race: The Carb Loading phase

Before an ultra, I take three days to up my carbohydrates and load sufficiently.

During these days, I arrange all of my meals in general to be more carb-based. This also includes my mid-morning and mid-afternoon snacks.

Each of us will need a distinct amount of fuel depending on different factors such as weight and metabolism. Here, I am going to use myself as an example. 

During a typical training week, I eat 11 portions of carbohydrates and fruit throughout each day, but, during my three days before racing an ultramarathon, that is upped to 21 portions, because carbs like glucose and fructose are the preferred fuel sources for our muscles.

Quite a big difference, isn’t it?

In addition, there are a specific number of fats, proteins, and vegetables organized into my meal plan, but let’s pull out and take a look at just the carbs

ultramarathon nutrition

My 21 portions of carbohydrates are broken up in the following manner throughout the day. I have included some examples of what constitutes as “1 portion of carbs” so you can get an idea of the quantities:

Breakfast: 3 carbs = 3 slices of toast, 1 sugar = 1 teaspoon of honey / 2 fruits = 1 large banana

Mid-morning snack: 1 carb = ⅛ cup granola / 1 dairy = 1 individual-sized yogurt /1 fruit = ½ cup strawberries

Lunch: 4 carbs: = ⅔ cups couscous + 1 cup sweet potato

Mid-afternoon snack: 1 carb = ¾ cup cereal / 1 dairy = 1 cups skim milk / 2 fruits = 1 banana

Dinner: 4 carbs: = 2 cups pasta

And can you believe these are only the carbs! Adding the correct portions of proteins, vegetables, and fats completes each meal. 

In addition to your nutrition, your hydration strategy for endurance exercise is key, too.

Be sure to stay well-hydrated during the days leading up to your race.

I add a sports drink full of electrolytes to my carb-loading days to aid my hydration and carb intake and to prevent hyponatremia, which can occur when your fluid intake is only water and electrolytes get depleted.

Ultramarathon nutrition

The Golden Rule of Race Day

As ultra runners, we need to apply the golden rule for ultrarunning to absolutely everything we do. 

Do not try anything new on race day!

This also includes the days previous when referring to food and hydration.

I am a creature of habit and follow this rule to a T. Why would I change something that works for me?

My pre-race dinner has been the same for the past 7 years. Even when traveling for a race, I cook and bring Giada de Laurentiis’s lemon pasta along with me wherever I go.

My friends may snicker at me while at the restaurant enjoying a meal out the night before the big day, but I don’t mind. There is no way I’m taking a chance of eating something that may not agree with me, putting at risk the outcome of a day I have worked so hard for. 

Ultramarathon nutrition

Now that we’ve prepared, let’s take a look at race day.

My Pre-Ultramarathon Breakfast

Now, I know it may seem excessive, but I eat breakfast 2-3 hours before any race – and recommend you do too – to be sure and give my body enough time to process the food.

My breakfast of champions for ultramarathons is a toasted bagel covered in honey (I also bring this along with me if I am traveling). 

Eating so far in advance will make you feel great for the race, but you may need a pick-me-up before the start. Therefore, I always take a gel about 15 minutes before the race starts to feel energized.

Ultramarathon Nutrition Tips: Race Strategy

Each one of us must put together our nutrition and hydration race strategy well before the actual race. What we eat and drink during our ultramarathon needs to be practiced repeatedly in all of our long runs during the training process.

I suggest you try absolutely everything out there to see what works best for you. There are countless gels, bars, gummies, carb and electrolyte-filled drinks on the market just waiting for you to test out. 

As ultra runners, it is also essential to try out solid food while training. During a longer ultramarathon like an 80k, 100k, 100 miler, your body will be begging you for some real food.

It’s helpful to try it out beforehand so you can get used to running while chewing a peanut butter sandwich. 

Ultramarathon nutrition

To calculate the number of carbohydrates needed during a race, use the following equation:

Weight in kilos = carbohydrates per hour you need to consume

In my case, I weigh 51 kilos, so I need to consume 51 grams of carbohydrates per hour during my races. It’s important to know that I am not talking about calories but grams of carbohydrates

No matter what you choose to consume, you need to ensure to take your total grams of carbs each hour to have a consistent energy flow.

On the back of each product, there is a nutrition label for your reference.

When checking, be sure you pay attention to the serving size the nutrition facts are representing. It’s easy to misread a label as sometimes it refers to a larger quantity of the product in the actual packet. This could inadvertently throw off your entire plan.

Gels can range anywhere from 16 – 25 grams of carbs depending on which ones you choose, and sports drinks also have a wide range of carb intake. That’s why it is imperative to check every single label and calculate your intake with care. 

Ultramarathon nutrition

Choose to consume what works best for you whether it be gels, carb-filled hydration, sandwiches, or a big old mix of things. 

Figuring out your nutrition race strategy may take a while, and there will surely be a lot of trial and error, but keep at it until you get it down to a fine art.

Most of us focus on training our body and mind, but training our gut is just as important.

The most important thing is to consume enough carbs during your race to not hit the wall. Controlling our food is one of the few things we have power over, so let’s take advantage of it and give ourselves the best shot at finishing our race happy and healthy!

Race Hydration

To figure out your ultramarathon hydration, take a sweat test. This will calculate how much liquid you will need to replenish per hour. 

When taking a sweat test, simulate your race conditions so your results will be as precise as possible. Take into consideration climate, especially when you will be racing in hot and humid weather.

After calculating your liquid loss, consume a minimum of 80% of that figure to keep you well-hydrated.

Ultramarathon nutrition

You Can Drink Your Carbs

I have had great luck drinking my carbs while racing, which kills two birds with one stone.

I get to hydrate while consuming my fuel at the same time. I don’t have to worry about carrying an array of products or eating much solid food. I do, however, bring something along just in case.

It’s always better to be over-prepared than underprepared.

Calculating ultramarathon trail race finishing times is not an easy task. Many factors can affect our time, such as rugged terrain and extreme weather.

How Much To Carry?

Always overshoot and bring more than what you think you may need. As a backup, you always have the aid stations to refill if you are low on fuel.

If you plan to use aid-station nutrition instead of bringing your own, be sure to know what they will have, and practice using those items beforehand to guarantee they work for you.

Post-Race Nutrition

To ensure a successful recovery, you must continue to fuel your body after an ultramarathon.

Everyone reacts differently upon finishing an ultramarathon; some can feel ravenous and others, no desire to eat at all. 

No matter what, take your recovery drink within 30 minutes after finishing and be sure and eat well to replenish your energy.

Ultramarathon nutrition

Do everything possible to assist your system in recuperating as best it can, to suffer as little as possible in the days to follow. 

Ultramarathon nutrition needs to be taken seriously to obtain positive race experiences and outcomes. Taking care of what you consume will enhance your performance and help you push to your maximum capacity. 

So let’s eat up!

Check out our guide to high-calorie snacks here.

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!

4 thoughts on “Ultramarathon Nutrition Guide: What to eat before, during, and after an Ultra”

  1. Hi Katelyn,

    Sounds like good advice and thanks for sharing.
    I wish I had stumbled over your guide before my first ultramarathon. Although I completed it and ran I time I am happy with, I don’t think I fuelled properly not knowing what I know now. It has left me with symptoms like chronic fatigue syndrome. I’m keeping positive, running slowly and very short and planing to get back to ultra running some day.


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