Having a nutrition strategy is key for any endurance sport, but it’s particularly important for ultra trail running. Not only are ultra trail runners going insane distances over brutal terrain, but they often have to carry all their own nutritional supplies—meaning there's no room for error.
In a recent Nduranz podcast episode, we sat down with Elite Trail Team athlete Kristian (Kris) Jones to break down the key nutrition challenges ultra runners face and how to overcome them. From maximizing carbohydrate intake to managing hydration and whether supplements work, here’s what you need to know to go the distance.
Weeks Before the Event
Start Planning Nutrition
Nutrition planning for an ultra trail event starts weeks before. You need to analyze the course, paying particular attention to wear aid stations are and where drop bags will be available.
Kris recommends using this information to break the race down into sections and make a nutrition plan for each, such as how many gels you'll need to carry for each section.
Create a Hydration Plan
One of the trickiest aspects of ultra trail nutrition to plan is hydration. According to Elite Trail Team Sports Dietitian Rebecca Dent, most ultra runners drink around 500ml of water per hour—but hydration isn't one-size-fits-all. Factors like climate, altitude, terrain, and individual sweat rate can all impact how much you need.
On top of this, access to water varies drastically between races. Some courses have frequent aid stations and natural water sources, while others require you to carry everything you need. If you want to drink a lot of water, you will have to carry a lot of water—which adds weight and affects performance.
"You really have to problem-solve for each race individually. At OCC in Chamonix, we had three aid stations, but also water spouts along the course where you could refill. You need to really plan it out section by section—how long it takes to get from one water source to the next and how much you need to carry to get there."
Practice Your Plan in Training
Race day isn’t the time to see if your plan works. You need to test your plan in training. That means training with the same fuels, in the same amounts, and under the same conditions you’ll face on race day. This way you know how your body will react so you don’t have unexpected surprises that destroy your performance.
Pre-Race Nutrition
Carb Loading for an Ultra Trail
To have enough energy for an ultra trail, you need to start fueling before the race even begins. Carbohydrate loading helps maximize muscle glycogen stores, giving you a reservoir of fuel to draw from during the race.
Start loading 24–36 hours before the race. During this period, aim for 10–12 grams of carbohydrates per kilogram of body weight. Focus on fast-digesting carbohydrates like rice, pasta, bread because they are easily absorbed.
In the final 24 hours before the race, reduce your fiber intake as it can linger in the GI tract and cause discomfort.
To learn more, see our Guide to Loading.
Pre-Race Breakfast
Assuming you’ve carb loaded properly, your muscle glycogen stores will be full when you wake up on race morning. But your body uses liver glycogen to fuel vital functions during sleep, which means those reserves will be partially depleted when you wake up. You need to eat a breakfast on race-day morning to top off that glycogen.
Ideally, you’d eat a breakfast of fast carbohydrates 2–4 hours before the start, so your body has enough time to fully digest it. The challenge is that ultra trail races often have start times early in the morning. It’s not realistic to eat breakfast at 2AM (prioritize sleep over a proper meal!).
Instead, aim to take in 1 gram of fast-digesting carbohydrates per kilogram of body weight for each hour you have before the race begins.
Also Read: Race-Day Breakfast Ideas
Consider Sodium Bicarbonate
Typically, sodium bicarbonate is used for short durations of high-intensity activity—such as a final sprint during a cycling race. This could be useful during certain sections of an ultra trail race. However, exercise physiologist Dr. Tim Podlogar doesn't believe it would really help on ultra trail races because they are so long.
However, Dr. Podlogar does think sodium bicarbonate could help with hydration. Because it contains sodium, taking it before a race can help the body hold on to more water—something that's important when you have to carry your own supplies.
Fueling during the Ultra Trail Race
Fast Carbohydrates Are Key
Just like with any endurance sport, fueling with fast carbohydrates is key to success. The body only has enough glycogen stored for approximately 90 minutes of activity. Ingesting carbohydrates keeps glycogen levels from depleting so you can go the distance.
Focus on "fast" carbohydrates because they are the ones that the body absorbs and converts into useable energy most rapidly.
New to endurance sports? Read our Guide to Fueling
Kris has an Nduranz Nrgy Gel 45 in his pocket for fuel.
Aim for 90 Grams Per Hour
When Kris Jones first started running ultra trail races, he consumed approximately 65 grams of carbohydrates per hour. His performance was okay, but he was "completely broken" by the end of races.
Exercise physiologist Dr. Tim Podlogar says that most trail runners should aim for 90 grams of fast carbohydrates per hour.
Kris actually consumes more than this. At the OCC in Chamonix, he had approximately 110 grams/hour, and his performance and recovery are better.
Pro Fact: The body can only absorb a limited amount of glucose at once, but fructose uses a different uptake pathway. To increase carbohydrate absorption, elite athletes fuel with a combination of glucose and fructose.
Choose Drinks and Gels Over Solids on Ultras
As a general rule, ultra trail racers should stick to liquid and gel fuels. These break down rapidly for quick energy without digestion issues. By contrast, solid fuels take longer to break down and can bounce around in the stomach, causing discomfort.
However, Kris points out that, after 5+ hours of racing, you sometimes just want something solid. There’s a psychological aspect to fueling and chewing can help boost morale.
But, if you are going to use solids, make sure they have these characteristics:
- No/Low Fiber: Fiber slows down digestion and can cause GI problems during races.
- Soft Texture: This allows you to chew them without throwing off breathing.
- Glucose-Fructose Base: These simple sugars are best absorbed by the body for rapid energy.
The Nrgy Juice Bar 22.5 is a solid fuel which is still suitable for endurance activity.
Gut Training Is Key
During exercise, the body diverts blood from the digestive system and to the muscles. While this is essential for the muscles to perform, the reduced blood flow slows down digestion and can cause GI issues.
Gut training is a way to avoid these problems. It involves strategies like gradually increasing carbohydrate intake so you can consume large amounts of fuel without issues.
Read about Gut Training Strategies.
Avoid Flavor Fatigue
Ever get 10 hours into a 15 hour race and suddenly are grossed out by the idea of consuming another gel? This is known as "flavor fatigue." Because it affects your ability to consume enough fuel, it can hinder performance.
There are a few ways of avoiding flavor fatigue, such as switching up gel flavors or alternating between drinks and gels. Kris says that using fuels with sodium also helps:
"If you just have all sweetness, it wears on the palate. But having that slight saltiness helps it go down better. Saltiness just makes you want to eat and drink, and when you're pushing these high amounts of fueling, it's really helpful."
Also read: How to Avoid Flavor Fatigue when Fueling
Bring Your Own Nutrition
One of the unique challenges of ultra trail races is that many don’t allow external crewing. You either have to bring all your own nutrition or pick up fuel and water from aid stations.
While it may be convenient, Kris’s advice is: don’t eat from the aid stations.
"The nutrition there is probably something you didn’t practice with, so you don’t know how your body will react. Further, you don’t know how long that orange slice has been sitting in the sun. It’s not worth the risk. Just bring your own fuel instead, even if it means starting with a very heavy pack."
Supplements for Ultra Trail Races
A ultra trail has gained popularity, we’ve seen a lot more athletes recommending supplements. But, as Dr. Podlogar warns, many of these athletes are sponsored by the manufacturers, which means they are incentivized to promote the product.
In his expert opinion, most supplements are not going to help ultra trail performance. He says to focus on dialing in training, fueling and hydration instead.
Which supplements are worth considering? According to Dr. Podlogar, one that definitely works is caffeine, though dosing properly is important for endurance events. He also says that electrolytes are important, especially for races lasting more than four hours.
Ultra Trail Nutrition Plan
Weeks Before
- Break the course into segments based on difficulty, aid stations, and drop bag locations.
- Plan nutrition for each segment, including fuel and hydration needs.
- Test your fueling strategy during training to see what works for you.
Days Before
- Begin carbohydrate loading 24–36 hours before the race.
- Target 8–12 g of carbohydrates per kg of body weight per day, focusing on fast-digesting foods like rice, pasta, and bread.
- Reduce fiber intake in the final 24 hours to minimize digestive issues.
- Consider sodium bicarbonate for pre-race hydration support.
Morning Of
- If you have 2+ hours before the start, eat a breakfast of fast-digesting carbohydrates.
- If your start is early and you have only about 1 hour, aim for 1 g of simple carbohydrates per kg of body weight.
During the Race
- Consume around 90 g of carbohydrates per hour, using a combination of glucose and fructose in a 1:0.8 ratio.
- Stick to gels, energy drinks, or soft-textured fueling bars for quick absorption.
- Hydrate with electrolyte-rich fluids.
- Consider caffeine for focus and alertness.
- Avoid relying on aid station food to prevent digestive surprises.
Want to hear more about ultra trail? Listen to the full podcast episode.