Is the Secret to Ultrarunning Success Downing Crazy High Carbs?

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This story was originally published on July 17, 2025.

IN THE SUMMER of 2024, runner and coach David Roche made a stunning announcement. He’d won a slot in the Leadville Trail 100 Mile, one of the oldest and most iconic races in the sport of Ultramarathon, which includes any race over 26.2 miles.

Not only is Leadville one of the most storied races, but it also had one of the oldest course records, which many people believe was unbeatable. But Roche was not one of them. He said he could beat the nearly two decade-old time of 15 hours, 42 minutes and 59 seconds.

The announcement was shocking for many reasons, but one stood out: Roche had never raced a hundred miles.

There were many doubters, including Roche himself. “I was so full of doubt and questioning,” he says now. “I had no idea if it was actually possible. But I knew based on the numbers that I could put out that if I was able to execute the way I thought could, then not only was the record possible, it could go down by a substantial margin.”

There were several reasons for Roche’s confidence. Ultrarunning is witnessing a number of innovations that are pushing times down: New carbon-plated trail shoes, advances in understanding the benefits of heat training, and the adoption of consuming sodium bicarbonate by elite runners to name a few.

But one innovation has garnered the most attention: The growing use of a “high carb” approach to training and racing, a tactic that started in cycling and is now moving into the rest of the endurance world, including ultrarunning.

Roche, as a coach and a runner, is one of high-carb’s leading proponents, and at Leadville he planned to consume between 120 to 140 grams of carbohydrates—around 500 calories—per hour. When he looked at his spreadsheet, it predicted he would beat the record by more than 15 minutes.

THE START LINE of one of ultrarunning’s most legendary races was, by some measures, an unlikely place for Roche to end up. He grew up in farming country on the eastern shore of Maryland. In high school he played football, weighed in at 200 pounds, and even played for Columbia University, where he studied environmental science. But after his freshman year, he quit football and started biking and running. He never imagined himself as a ultrarunner

“I used to think that my best event would be 800 meters and anything above that, I would get progressively worse, because I come from a football background. I always assumed it wasn't going to be my skill set.”

After college, when Roche moved to North Carolina to study environmental law at Duke University, he started running on the trails around Durham. He also met his wife Megan, who was studying neuroscience and playing field hockey. The two started frequenting the trails around the city together and both got more into running. Roche started doing trail races, and started coaching. In 2018, after Megan finished her medical program at Stanford, the two moved to Boulder, Colorado, where they both coach full time.

Roche had always advised his athletes to “shoot their shot” and go for big goals. But life was catching up. The couple had their first son in 2022, and time was slipping by. So in early 2023, Megan gave him a wakeup call. “She was like ‘David look: You're 35 and who knows how many years you have at the top level. Start to do what you say and shoot your shot.”

That April Roche signed up for the Canyons 100k in Auburn, California, which is a “Golden Ticket” race for the Western States 100 Mile, the most prestigious race in ultrarunning. The race went well, until he took a gel from an aid station that didn’t agree with him. He immediately vomited, then couldn’t keep anything down and ended up walking for six miles, finishing in fifth place. He knew he needed to figure out exactly what nutrition would work.

At the time, Roche was reading about, and experimenting with, higher levels of carbohydrate intake which had become standard in elite cycling, even though it was assumed that the body could only process 60 to 90 grams per hour. More fuel allows you to sustain a higher effort for longer.

Trying different gels and drink mixes, he pushed his carbs up to 120, 130 and 140 grams per hour. And in December of 2023, he entered the McDowell Mountain Frenzy 50 Miler and won. By the summer of 2024, he was ready for the Silver Rush 50 mile in Leadville.

He won by 25 minutes, and earned a slot in the Leadville 100 mile.

ROCHE KEPT TRAINING, both his legs and his stomach, taking in carbs at levels many regard as controversial. But even as he did, getting to the start line of Leadville was itself a kind of victory for other reasons.

In training, Roche only runs five days a week (and at lower mileage than most elite ultrarunners, with a focus on speed). Some days he rides his bike, which is what he was doing in April of 2024 when a car turned into him and sent him flying into a fence. He woke up with a concussion and a broken wrist. But as soon as he was recovered enough, he kept training (running with his arm in a sling) and keeping up the carbs.

“I trained like a competitive eater,” Roche says, learning to take in the amount of fluid and gels he’d need. “People in the competitive eating world actually practice with fluids, because they don't want to eat hot dogs every day. So I would use fluids to practice the bloat and teach my body not to reject that amount, because I knew I'd have to take in up to 56 ounces per hour and not reject it.”

By August, Roche was ready in his body. In his head, slightly less so.

“I still had so much doubt about whether it was possible or even a worthwhile goal to chase, with kids and work all the stuff going on,” he says now.

But Megan did want him to race, and so at 4 a.m. in Leadville, when the starting gun went off, he pushed those doubts aside and focused on the numbers. Not long after the start, he checked his heart rate.

“I knew how many calories-ish I burned at certain heart rates,” Roche says. “And when I looked at my heart rate, it was saying: ‘Look, you can go faster and still replace your calories.’ So a few miles into the race I was like, ‘All right, I guess it's time to race now.”

Roche made a rule for himself that he had to run every step of the way, with no walking. He describes the race as “incredibly fun,” which is not something people usually say about 100-milers.

“We saw him at Twin Lakes (mile 40) the first time and he looked great,” says his pacer Teddy Bross. “When came back into Twin Lakes (mile 60), in all honesty, he looked about the same.”

Bross ran the last 40 miles with Roche, and says there was one touch-and-go moment on the “power lines” climb where Roche started getting nauseous. But he was able to slow down, breathe and get it under control. Then the two runners sped on.

“On flats and downhills, I think we were somewhere around seven minutes a mile,” says Bross. “We were cooking,”

As they approached the finish line, Roche’s gap over second place widened. By the time he crossed it, he’d beaten his own prediction by one minute.

His time of 15:26:34 beat the Leadville record by more than 16 minutes.

THERE ARE MANY opinions on the so-called “high carb revolution,” or “carb mania,” as Alex Hutchinson, author of Endure: Mind, Body, and the Curiously Elastic Limits of Human Performance, calls it.

“The high-carb stuff is very much an open question scientifically,” Hutchinson says, “There's some logic, some anecdotes, and a tiny bit of data, but there are also lots of reasons to be skeptical. The thing with ultrarunning is that it's pretty much impossible to run randomized trials where people do all-out hundred-milers over and over. Everyone is making some guesses and doing some self-experimentation, but some people are more willing to try longshots.”

Andy Jones-Wilkins, a coach who has been running ultras since the 1990s, has seen a lot of trends come and go. He calls the push for high-carb fueling an "incredible marketing opportunity” which companies are taking advantage of, but cautions that it might not be the best strategy for mid- and back-of-the-pack runners.

“For athletes who are maybe a little older, in their 40s or above, somewhere in the range of 60 to 70 grams of carbs is per hour is plenty, especially if you're going to be going for more than six, seven eight hours.” The main issue, he says, is gastrointestinal distress, since slower runners aren’t working at the same intensity as elites, and just don’t need as many carbs.

“We know that ultras give people enough GI tract problems,” says Jones-Wilkins, “And to add to that by encouraging people to pump in over 100 grams of carbs, I would just urge people to tread carefully and experiment, because there's all kinds of stuff that can happen when you're eating a gel version of Thanksgiving dinner, then trying to run.”

Jason Koop, author of Training Essentials for Ultrarunning, says that while high-carb fueling seems new, it’s not. “The pro peloton [in cycling] has been doing this for years,” Koops says. “So anybody who thinks they're doing something new is either fooling themselves or hasn’t been paying attention. The origin of it is in very high-performance cycling, of which extremely few humans on the planet actually have a need to—or even can—ingest that amount of carbohydrate.”

Tyler Fox is a coach and a runner (coached by Roche) who’s had some success at the “lower end of high carb,” And while he does recommend higher carb intake for his athletes, it’s with a lot of caveats, including an athlete’s fitness and ability to maintain intensity.

“I think the narrative should be ‘fueling the work,’” Fox says. “Because if you're not able to sustain things from a mechanical perspective you're limited later by your ability to put out power.” According to Fox, in a 10-hour race, if you can run at a high intensity, you're going to be able to use more carbs, “but if you run at a conservative, less taxing output, your burn rate is going to be lower. And that's where you could run into high carb backfiring.”

In other words, if the carbs aren't being burned, they’ll find a way out though other channels, and you're risking a blowout on the side of the trail. Still, Fox sees the upside to higher carb intake with nuance. “I'm not suggesting that it's exclusively for higher level athletes” Fox says. “It does allow you to do more work, if you're prepared for it. But your training has to support it.”

Anna Gibson, a track and sub-ultra trail runner also coached by Roche, is sold on the benefits of high-carb fueling, and definitely has the training to support it. Last year the former NCAA athlete ran a 1500 meter PR, and competed in the Olympic trials. “In my last race I was putting down 110 grams of carbs per hour,” Gibson says. “It definitely took a lot of gut training to get to that point. But I credit that with my increase in performance.”

That race was the Gorge Waterfalls 30k, in which she won, broke the course record and finished second outright.

Despite all the unknowns, there’s no doubt that Roche’s output is enough to burn whatever he can cram in. “I think David has a clear understanding of what the science shows,” says Hutchinson, “and, just as importantly, what it doesn't show. Some people might look at that evidence and say, 'Nah, not quite enough to convince me to try it.' But David's an optimist: he weighs the odds and says, 'So you're telling me there's a chance!'

For Roche, it’s changed the game.

“I used to always think that I just sucked at the end of long races,” he says, “I can remember so many 50ks where I was like, 'Well, if I'm dying at mile 26, why would I go farther than this? Clearly I'm fighting my physiology.’

“Then I essentially went from normal fueling to high fueling and all of a sudden I become one of the best. So at the end of the day, it's really just: You give me 75 gels and I can give you the world.”

BACK HOME AFTER the Leadville 50, Roche’s recovery was fast. He says that after a day of feeling terrible, he improved quickly. In a couple weeks he was back to running form, which he attributes to his high-carb approach.

“I think the magic of carbs isn't race day performance necessarily. It's how much it helps you adapt and recover from training styles that will level up your fitness over time. So I'm going to be able to respond better to this workout, then come back stronger from it and stack up training in a way that makes me 36-years-old going on 22. “

Yet even as he recovered, Roche started to wonder if he got lucky in Leadville. “I thought, ‘What if it was all a fluke? What if I didn't actually learn anything about high-carb fueling or training or anything? What if I just had a good day at the right time and basically it was the stars aligning?”

To banish his doubts, Roche signed up for the Javelina Jundred in Arizona, just two months after Leadville. The race would be hot—nearly 100 degrees—so he started heat training, and practicing getting more fluids in.

At Javelina, Roche flew through the course, winning in 12:45:04 and missing the course record by less than two minutes. “The difference between Leadville and Javelina,” Roche says, “is that at Leadville, even in the moment, it felt like something magical was happening. It felt like something I don't know if I'm ever going to be able to repeat. But at Javelina I felt like I could do this any Saturday.”

The victory also earned him a “golden ticket” to the prestigious Western States 100 Mile.

Roche continued training and racing through the spring of 2025, with some of the usual ultrarunning ups and dowsn. In March he sprained an ankle in the Big Alta 50k, and had to drop out. But in May, he raced the Quad Rock, 50 Miler, winning by over 40 minutes and setting a new course record. The win gave him a “huge boost in confidence” for Western States in June.

WHETHER HIGH-CARB fueling will work for most runners remains to be seen. While there is some indication it might be different from previous fads like barefoot running, fat-adapted training and so on, runners should still proceed with care.

“Your average ultrarunner,” says Koop, “and even your good ultrarunner, needs to be cautious about titrating this up just because they saw somebody on Instagram do it. In many cases it's not necessary based on the energetic demands, and in most cases it’s not even pragmatic, because they can't take in that much carbohydrate.”

Jones-Wilkins agrees. “My prediction is that we’ll see kind of a settling into the fact that high carb works for the elites, but it doesn't work for the vast majority of people. They'll settle somewhere in the middle. But I urge athletes to tread carefully and experiment with what works for them. Because what works for me might not work for you and might not work for the next guy.”

ON JUNE 28, Roche lined up with some of the best in the world including legendary mountain runner Kilian Jornet, who won the race in 2011. This time, he wasn’t making any bold predictions.

“I’m a big-time underdog,” Roche said before the race, “even an underdog for top five. And that's the way I like it. I know I can run fast there relative to historic times. It's just a question of how fast everybody else goes.”

They went out very fast, with Roche in the lead up initial four-mile climb. Then as they moved through the mountains, a pack of at least twelve elite men pushed a sub-record pace. They hung together for the first 30 miles, all running within a minute or two of each other.

Roche was in the mix, hovering around fifth place, running shoulder-to-shoulder with Jornet and the others. The race was going according to plan. By mile 40, in the heat of the day, things started to spread out. At mile 40, Roche came in right behind race leaders Chris Myers and (eventual winner) Caleb Olson. At mile 56, he was solidly in fifth place.

“I felt great almost the whole time, even when I came into Michigan Bluff right behind Jeff. I was in a great spot. In retrospect, I was in the ideal spot.”

But soon after leaving the Michigan Bluff aid station, on the downhill, Roche’s race also started going downhill. He suspects he took in too many electrolytes given his heat training. But for whatever reason, his vision got blurry and he had some minor GI distress. So he dialed down the carbs, which he now thinks was a mistake.

“I went lower when I should have gone higher,” he says. “The gels were going down fine. But even after that I was able to recover once my sodium levels got better. I moved up and felt great. Then the lack of gels hit me, and that lead to some problems on the mental end.

Roche started fixating on his health, catastrophizing, and was suddenly filled with anxiety about seeing his kids again. He hesitates to call it a panic attack, but when his pacer, Teddy Bross (who is a physician) gave him some breathing exercises, they helped. Looking back he feels like he prepared his body, but not his mind.

“I think because of life being so white knuckled with two young kids and everything,” he says, “I didn't do the basic stuff I always ask athletes to do as a coach—like make it okay to get to that place where it feels kind of scary. Basically, I didn't nail down the mental side as much as I needed to going into a 100 mile.” He ended up dropping at 62 miles.

But as every ultrarunner knows, DNFs are just as important as getting on the podium, if not moreso. “The magic of ultrarunning,” Roche says, “is that you get stripped down to your core and from that you can grow back stronger. So I'm excited to get back out there and do another 100. And if I do qualify [for Western States] again, you’d better believe I'm coming back.”

Editor’s note: After the initial publication of this article, Roche reset his Leadville 100 record in August 2025, running a time of 15:12:30.