The UTMB Finals in Chamonix present a formidable challenge, with a route that typically takes over 40 hours to complete. Along the way, runners encounter aid stations brimming with an assortment of cured meats and local cheeses. With just five crew access points and a single drop bag, figuring out the most effective fueling strategy for an ultra like UTMB becomes the ultimate conundrum.

The author of this article, Will Weidman, coach at Uphill Athlete, has finished UTMB (106-mile) three times, twice in the top 75 (out of 2,700 participants), and as the 3rd American in 2021. He has coached numerous athletes to success at UTMB, CCC, and OCC. Read his top 5 tips for UTMB training here

Will is racing the 106-mile distance at the UTMB 2023. He shares firsthand insight on why fueling during UTMB is uniquely challenging and his top tips to fuel for success. Will lays out when and how to fuel so you reach the finish line strong.

To understand how to get an entry into UTMB, check out our article here. 

A male runner hiking uphill with poles in both his hands.
Due to the UTMB Finals course's difficulty and remoteness, aid stations are spaced farther apart compared to other races.


Considering the multitude of challenges the race brings forth, let’s delve into a select few that pertain to fueling. The risk of bonking and experiencing fatigue is significantly heightened if not executed correctly.

Minimal Crew & Drop Bag Access

With the Tour de France atmosphere in towns UTMB passes through, it is easy to forget that most of the UTMB route is remote and inaccessible.

There are only five places where you have crew access: Contamines, Courmayeur, Champex-Lac, Trient, and Vallorcine. Courmayeur has the only drop bag throughout the course.

Contamines to Courmayeur and Courmayeur to Champex-Lac are particularly long stretches between support, taking most runners 10+ hours.

Time Between Aid Stations

Due to the difficulty and remoteness of the course, the time between aid stations is longer than in many other races. For example, between Chapieux and Lac Combal, runners climb and descend two difficult mountain passes in the night. This means four hours between aid for most runners.

Aid Station Fare

Those who haven’t raced in the Alps may be surprised by the options at UTMB aid stations. Staples include cured meats, local cheeses, and fruit. There are no gels and minimal hot food options.

Major aid stations like Courmayeur and Champex-Lac have a bigger spread, but remote locations like Bertone or Lac Combal are more limited.

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To sustain optimal performance on the course, consuming over 15,000 calories along with the necessary fluids and electrolytes may be necessary. However, managing such a feat amidst these challenges can be a daunting task. So, how does one rise to the occasion? Let’s discuss strategies to succeed below.

Rely on Your Crew

Aside from races in the Alps, I haven’t used crew in a race since 2008. Between great aid stations and plenty of drop bags, I find it easier and simpler to self-support. UTMB is a different story. I have relied heavily on my crew for each of my three finishes. They resupplied my nutrition products at each crew access point, and with only one drop station, I could not have carried enough nutrition supplies otherwise. A variety of nutrition options is also paramount for a race this long. My crew provided a wide range of food choices, including avocados, chips, hummus, peanut butter, Nutella wraps, and grapes.

While you need to fuel steadily throughout the race, getting in a large amount of nutrition at key aid stations is important.

In Champex-Lac in 2019, I consumed nearly 1,000 calories in the aid station alone, which was some much-needed fuel after 20 hours of constant movement.

Listen to our podcast on crewing and pacing in trail running here.

Les Houches in the foreground with Chamonix in the distance.
At UTMB, you can have sweltering weather in the valleys during the day, and freezing temperatures on the mountain passes at night.

Bring More Nutrition on the Trail

In races with frequent and well-stocked aid stations, you can get away with having a few gels and a few bottles on you. You simply need to carry more nutrition on you at UTMB. I bring more than 2,000 calories with me coming out of Contamines and Courmayeur. Depending on the weather and your individualized hydration needs, you may also need to bring more fluids than usual. I often race with just two front flasks totaling one-liter capacity, but I’ll bring a third flask on the longer sections. In hot weather or if you have higher hydration needs, you may also need a hydration bladder.

Optimize Your Nutrition Product Mix

2019 was a hot year at UTMB. I started to feel off after Saint Gervais, only 20km into the race. I struggled on the relatively easy section to Contamines and was frustrated by having to run the few flat miles coming out of Contamines.

As we ascended to La Balme, I was in full-on crisis mode and felt dizzy, nauseous, and weak. Runners were passing me left and right. The idea of another 85 miles and 28,000 feet of climbing seemed preposterous.

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I thought back and realized I had been sweating in the hot weather for four hours. The aid stations didn’t have many electrolyte options, and I realized I was likely low on salt.

I took an electrolyte cap, followed by a longer stop than usual at La Balme for some salty soup and crackers. I kept on a regimen of salt intake and soon felt strong again, working my way back up the field.

Weather is highly variable at UTMB. You can have sweltering weather in the valleys during the day, and freezing temperatures on the mountain passes at night.

Combined with the limited options at aid stations and sparse crew access, you need to adjust your nutrition intake accordingly and make sure you are still balancing calories, carbs, electrolytes, and fluids.

Test this out as much as you can in training.

Stock Up in Towns

In 2021, I started to bonk hard coming down Gran Col Ferret. My stomach was upset, and nothing looked good at La Fouly. I trudged onwards to Champex-Lac in rough shape. Suddenly a light bulb went off, and I called my crew to see if he could track down a pizza to bring to Champex-Lac. He had a delicious pizza waiting, and it turned my race around.

Palette fatigue is inevitable in these long races, especially with each aid station having largely the same fare.

If you have crew, try to have them bring some other options that you think you’ll like – pizza, focaccia, panini. You have cell reception on much of the course, so you can call ahead.

Many towns and restaurants close down early, so it’s good to plan ahead and ensure you get what you need before night falls.


It is as important to train and plan your nutrition as it is to train your legs and lungs. For me and the athletes I coach, fueling is the biggest driver of success at UTMB.

Learn the concepts of training for trail running.

Plan ahead, know how long you have between sections, and bring what you need. If you have a crew, rely on them to resupply your nutrition products and provide some different options for you in the aid station.

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