Fueling for 50k to 100k

March 5, 2021

Dear Chaskis,

How do you fuel when racing and training ultras? How much should I be drinking during the race? Do you eat junk food? Please help!


Many a curious ultra runner

I love food and I care about my performance and I meet tons of runners in the same boat. How do I eat “healthy” as an athlete running 150 miles per week? How much protein, carbohydrate, and fat should I be consuming? What’s the best food to fuel my body when I’m running for 6+ hours? Do I have to give up ice cream?

Real Ultras

After I published my last installment in this nutrition series (Fueling for 50K), I got a lot of comments from readers who told me that, to them, my recommendations made more sense in the context of a marathon than an ultra race. From a time perspective, I was writing about a fueling for a race that would last less than three hours.

So, by popular demand, this is my take on fueling for races of 5-10 hours or 50km-100km.

Ty before his first 6+ hour effort to set the Inca Trail FKT in August, 2019

Day-to-day Fueling

If you’re going to run a 6+ hour race, you’re a pretty serious runner in my book. So, you already know that your training is going to require a different level of nutritional support than if you were just brunching without the long-run on Sundays.

That said, I don’t like to prescribe rules about calories or macronutrients because, just like with training, I know that everyone is an individual and it’s practically impossible to actually track your caloric expenditure and intake with any level of accuracy.

Luckily, we have a solution for that.

Trust the Body

The simplest way to figure out how much to eat, as well as what to eat, is simply to listen to your body. Our bodies are pretty good at telling us how hungry we are and what we’re craving—salty vs. sweet, protein vs. carbs, etc. As long as you aren’t eating super calorically dense food (where your body might not be able to realize how many calories you’ve consumed before you finish that pint of Ben & Jerry’s), if you simply eat until you’re full, you’ll be good to go. Pro-tip: if you’re having trouble with this, just eat slower. Sometimes the body just needs a minute to catch-up.

Don’t Stress about Body Image

Ultra-runners come in all shapes and sizes, even at the elite level. There’s a reason that the winners of UTMB don’t look like the winners of the Boston Marathon. Ultra racing prioritizes different strengths than road racing and your ability to withstand hours and hours of pounding and process calories while running is way more important than whether your body fat percentage is 6%.

Full disclosure—I’ve personally had issues with eating disorders and my relationship with food. If you’re running to lose weight, I’d recommend you make sure that’s backed by a desire to be healthy and has been OK’d by a doctor. Be careful, and if you’re struggling with negative thoughts about your body, don’t be afraid to reach out to family and friends or medical professionals.

Eat the “Healthy Stuff” First

If you want one real practical tip, here it is. Yes, when I’m in a big block of training, running 20+ miles per day for weeks on end, I’ve been known to have a large bowl of ice cream every night after dinner. But, even then, I try to fuel my body with “healthy food” before that.

What exactly is the "healthy stuff"? I think a general rule is things that come from the Earth vs. a package. Fruits, vegetables, fish, chicken, lean-meats, and carbohydrate-rich foods like rice, potatoes, sweet potato, or sourdough. If I’m still hungry and craving after I eat a reasonable amount of the good stuff, I have no qualms with reaching for the Phish Food.

[Editor's note: I have no promotional connection w/ Ben & Jerry’s. But seriously, totally open to that sponsorship. Hit me up.]

A standard Ty breakfast - fruit, greek yogurt, bagel, hummus, tomato, smoked salmon

Pre-Race Prep

The most important thing to figure out before race day is what you’re going to use for fuel in your race and how much you’ll try to consume per hour. When I moved from 50km (or races under 3h00) to 100km (or races around 6 hours), I reached out to my ultra-running friends and they all told me it was important to have multiple fuel options, and not just to rely on gels—I mean, the body and the mind can only take so many gels.

Experiment, Practice, Refine, Repeat

Chaski Director of Coaching and my long-time coach, mentor, and friend Jon Waldron often says that every time you train an athlete, it’s an “experiment of one.” I think this is even more true for fueling. Some people have tons of trouble getting two gels down during a marathon while some are able to eat a piece of pizza while running 6:00/mile pace.

My suggestion? Experiment. Start on your easy days. How does a gel go down? What about a couple Oreos? How about some Swedish fish? Don’t let anyone else tell you what to eat, but the important thing is to try lots of things and see how they taste, how literally easy or hard they are to chew/swallow while running, whether or not you can keep them down while running your target pace, and how well you can track the caloric content of each item.

Know Your Body’s Caloric Limits

Speaking of which, lots of sites will tell you your body can consume and process about 250 calories per hour. That’s a gel every 24 minutes.

In reality, some ultra-runners like my friends Jim Walmsley and Patrick Reagan have been known to consume double that. Again, it’s a matter of experimentation. You want to consume as much as you can for a long race without making yourself sick. Can your body tolerate 300 cal/hour? What about 350? These are the experiments you can run in training.

You’re never going to fully replenish the amount you burn, even at 500 cal/hour, but the smaller you can keep your increasing deficit, the better you’ll be in the long term.

Get a Crew

The ultra world has the best community in Endurance Sport (no bias, obviously). Part of that comes from the fact that we often rope our family and friends into standing around in the middle of the night to cheer us on and hand us burritos.

Seriously, though, I never realized how valuable having a crew was until I helped my friend Patrick Reagan when he won the US 100 Mile Trail Championships last year. Even in a 100 miler, Pat hardly ever stopped for more than 60 seconds at our aid station, as each time we had everything perfectly dialed.

This is why the ultra community is so strong! We get to relax and hang out while Patrick Reagan was out crushing the 100-mile Trail Championships

Beyond the precious minutes you can save, having smiling faces every few miles is the best way to stay positive and motivated.

Race Day Specifics

Keep It Simple

In my last post, I wrote about the system I used for timing my gels. In longer ultra-races, I keep it simple.

I set my watch alarm to go off every 20 minutes, and then I eat 100 calories. That’s it.

Obviously, you’ll want to adjust this to your own fueling needs, but I’d really recommend this strategy as it takes all the thinking out of fueling.

You Don’t Need to Eat Real Food

I know, I know, I’m coming from a road background and the more seasoned ultra-runners might chew me out for this one. I’m not saying you CAN’T eat real food (e.g. sandwiches, burritos, pizza, etc.) but you don’t HAVE to eat real food.

Personally—and from many others I’ve talked to—I’m able to rely on simple fuels like Honeystinger’s (disclosure: they’re my sponsor) gels, chews, and waffles and, of course, Oreos (not my sponsor, but see below) for races up to 6-10 hours. Heck, in the aforementioned 100 Mile Trail Championship race, Patrick Reagan only consumed gels, waffles, and sports drink for 12.5 hours.

Aside - what’s with the Oreos? If you’ve read any of my race recaps, you know that I often fuel w/ off-the-shelf Oreos during long efforts. The reasoning is simple: (1) They go down easy for me. (2) They’re easy to measure; two oreos is usually about 100-120 calories. (3) They’re available everywhere on Earth; I’ve been able to get them in rural Ecuador and Nepal. (4) They’re really cheap.

[Still waiting on my Nabisco Sponsorship.]

Hydrate—and Don’t Forget Salt!

Someone could probably write an entirely separate post (or book) about hydration, and I’m going to be a bit hand-wavy here because I’m not an expert.

Don’t over-hydrate and don’t under-hydrate. Drinking too much water (and not consuming enough salt) can be fatal due to hyponatremia. Dehydration is also real and thus it’s important to drink to thirst. Generally, I recommend listening to the body here and always consuming something that has salt in it, whether that’s a high calorie sports drink or an electrolyte mix like nuun (disclosure: a sponsor).

When I imploded spectacularly at Project Carbon X in 2019, going after the 100K world record on a hot day, a big part of my failure was due to inadequate salt consumption. Hydration and salt balance is another thing that I’d say you really need to perfect in training.

The face of not hydrating well enough

The Legal PED: Caffeine

This is another personal one (see the note below), but there’s lots of science that shows that caffeine has real and positive benefits on performance.

Personally, for a race of 6 hours, I often hold off on caffeine (other than my normal pre-race coffee) for the first 2 hours of the race. This forces me to start out more relaxed and gives me something to look forward to in the later stages of the race. I then take either 1 Honeystinger caffeinated gel (about 32mg of caffeine) per hour or, for longer events, I’ll take a 100mg caffeine pill every 3 hours.

Note: Please make sure you understand your body's ability to intake and process caffeine before you try anything in a race. This is what I do, but it's based on my body's tolerance of caffeine. Do not consume high amounts of caffeine without first making sure your body can process it safely.

After the Race

Don’t force it

I often fantasize about the giant pizza or ice cream sundae I’m going to eat as soon as I cross the finish line and then am surprised to find my stomach in knots, barely able to tolerate some pretzels and nuun for the next couple hours.

It’s okay. You’ve put your body through the ringer and there’s some crazy shit happening inside you once you finish. Be patient. I often find the day after a race is when the real refueling happens.

Ty's first real meal, several hours after winning the US 50 Mile Road Championships (Oct., 2019)


Dude, you just finished an ultra! Insane! Celebrate! Whatever that means to you, make sure you enjoy the moment, let loose, and make some memories that you can look back on next time you’re in the middle of a long training run and thinking about the next race.

Even Longer?

What about hundred milers? What about multi-day races?

Now, we’re really getting outside my realm of expertise. I did spend almost 24 hours in continuous motion when I set the Everest Base Camp Trail FKT back in March, but I’ve never run a hundred miles (or longer) and I’m not the expert.

The good news is that we’ve got an unprecedented diverse team here at Chaski and with studs like Kris Brown (top 10 at Western States) and Pete Kostelnick (world record holder for running across America), I think we can get you your answers.

Stay tuned!

What do you think? Is there anything we missed? Anything you do differently? What questions do you have for Ty or the other Chaskis?

Feel free to comment below or shoot us an email at to get an answer from a real, live human.

Happy fueling and happy racing!

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Tyler Andrews

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