Skip to main content

How to Run 100 Miles on Almost No Carbs: Interview with Ultra Badass Zach Bitter

Have you ever run a seven-minute mile? How about 100 of them? Zach Bitter did when he set the record for the fastest 100-mile race.

Today, the 32-year-old ultrarunner is planning his next long haul at Western States 100, which was the track for his first-ever 100-mile race back in 2012. Although the route is considered one of the most difficult ultras in the world, Bitter is gunning to drop his record time from 16 hours, 53 minutes to below 15 hours.

Image used with permission by copyright holder

Bitter sat down with The Manual to share his epic training schedules and unique fuel plan — which includes almost no carbs.

Recommended Videos

Training

When Bitter plans his daily afternoon run in his home of Phoenix, Arizona, he says what no mere mortal would say: “I try to pick the hottest time of day.” That means 30-60 minutes of mountain sprints in the blazing 99-degree Fahrenheit heat.

Image used with permission by copyright holder

Bitter’s sweltering afternoon run comes after a morning run session roughly two hours long, and is followed by evening strength training at the gym. “During this peak training I hit upwards of 20 hours of work a week,” Bitter says, adding that his key to success without burnout is constant hydration before, during, and after workouts, and an Atkins low-carb lifestyle comprised of healthy fats, moderate-protein, high-fiber, and (of course) low-low-carbs.

Wait … so no carb-loading with pasta and pizza? I thought that was an integral part of being a long-distance runner!

Nutrition

“Whether or not I’m training, the piece that stays consistent in my diet is using fat as a primary micronutrient,” Bitter says. Week-by-week, depending on the intensity of training, Bitter adds or subtracts low Glycemic Index (GI) carbs like sweet potatoes, melons, and berries.  Developed by researchers at the University of Sydney, the GI ranks carbohydrate foods by how quickly they get converted into glucose in your body, with the goal being a slow, steady stream instead of a rush.

On other weeks, Bitter drops his carb intake to a ketgoneic — or keto — phase, relying on fats as the primary fuel. Most runners scream blasphemy at the idea of working out without carbohydrates, but Bitter has been doing it since 2011 after completing a full ultra marathon season of three 50-mile races in the span of nine weeks

ThitareeSarmkasat/Getty Images

“I fell in love with the sport but started noticing it was getting harder to recover. Big energy swings left my energy crashing. Then I was introduced to Dr. Jeff Volek, who has been one of the forefronts experts in the low-carb movements. Volek was very influential in helping me lower carbs then tweak my diet to degrees of different phases for my training.”

Hot to Go Keto or Low-Carb

“Take away any refined carbohydrates and sugar,” Bitter says, who moved on to removing all grains and breads. “I can count the number of times in a year I’ve had bread or grains on my hands,” he adds.

When starting a keto or low-carb meal plan, Bitter says you can expect a three- to four-week “induction phase” during which your body begins to relearn to use fat as a primary fuel source. During this time, he urges you to pay attention to keeping carb intake as low as possible so your metabolism can make the switch and get good at burning fat. After that, low GI carbs can be moved in and out in small proportions.

Zach’s Grocery List

• Fatty cuts of meat
• Dark, leafy greens
• Spinach
• Broccoli
• Brussels sprouts
• Asparagus
• Carrots
• Sweet potatoes
• Berries
• Melons
• Clarified butter
• Coconut oil
• Cheese (raw)
• Nuts

Some runners and exercise scientists have condemned keto for long-distance runners (especially for women, whose reproductive system can react negatively against the elimination of carbs), but Bitter has seen tremendous success with a high-fat, low-carb diet.

“At my absolute leanest, around 4 to 5 percent body fat, I still have enough fat to get through a long event because it’s a bottomless pit of fuel,” Bitter says. “Glycogen stores can be eliminated quite quickly, and when you rely on these, you can bonk. However, if your body is used to readily accessing body fat, you can power through the long haul.”

Bitter compares carbs and fat as two different fuel tanks. “Would I rather access a limitless source or one easily depleted?” And unless you’ve been living under a rock for the past 10 years, you should already know that the demonization of fat in the food industry has been pure marketing tact.

Bitter talks about his nutrition at length on his blog and social media, and is always responding to people who post questions or concerns. “I love getting into the weeds about how and why low-carb works,” he admits.

Jahla Seppanen
Former Former Digital Trends Contributor, The Manual
Born and raised off-the-grid in New Mexico, Jahla Seppanen is currently a sports, fitness, spirits, and culture writer in…
Cold for 8 days, light to carry, and modular: Dometic’s new cooler changes the game
This modular cooling system might just be your solution for a hot summer
Dometic Recon Cooler

Cold, refreshing drinks are perfect during those hot summer adventures, but it can be challenging to find a great cooler system to bring with you, especially on a multi-day journey. Dometic, an outdoor tech company, has just introduced Recon, a stackable, modular cooling system designed to stay cold for up to eight days.

One of the most exciting aspects of Recon is its compact design. “We’ve all wrestled with coolers that don’t stack or fit. Recon fixes that,” says Josh Militello, President of Segment Mobile Cooling Solutions at Dometic. “It’s cold storage that packs tighter, stacks cleaner, and moves easier. No wasted space. No extras. Just a system built for how people actually roll.”

Read more
Why Spokane is one of the Pacific Northwest’s most underrated outdoor destinations
Spokane is high luxury, but it's interconnected with the outdoors
View from the Numerica Sky Ride in Spokane

I've lived in Washington State for a couple of years now, but I'm still unpacking all of the great places to stay and visit. There's so much to do in the Evergreen state, and during my recent stay in Spokane, I can definitely say that there are a lot of high-end luxury experiences too. From high-end hotels like the Davenport Collection and eateries to some of the best wines in the state, you might be surprised to learn that Spokane is actually a top destination for nature lovers, too. Here's everything you need to know about the wilder side of Spokane and why you should consider coming here during your next vacation.
Outdoorsy things to do in downtown Spokane

This city is a particularly unique place because the town was built around the Spokane River. This is a gorgeous ribbon of blue that's full of waterfalls, eddies, and streams that wind their way through the city. The best place to see this is in downtown Spokane, specifically at the famous Riverfront Park.

Read more
Looking for adventure and culture? This city is the best in the world for urban hiking
Here's the world's #1 city for outdoor lovers
Rio de Janeiro

As an outdoor enthusiast, one of the top things I look for in a travel destination is proximity to the outdoors. I'm certainly not averse to pitching tents, but sometimes it's nice to mix in a bit of urban excitement to my travels. Sports Shoes, a UK running retail brand, just completed a study that analyzed the top urban areas for hikers on break. My personal favorite hiker-friendly city is Seattle, which squeaked in at number 12. The number one spot goes to Rio de Janeiro in Brazil.

The winner was decided through two primary variables: the number of hikes in the area and the average rating and reviews of those hikes. This was averaged out into a hikeability score out of 100, and the only one to get a perfect score was Rio de Janeiro. With a total of 334 hikes averaging a rating of 4.8 stars, this city is officially the world's number one urban area for hikers.
Top hikes in Rio de Janeiro

Read more