Who is Zach Bitter? Legendary Ultrarunner Profile

Zach Bitter is an American ultramarathon runner who has held the world records for the 100-mile run on a running track, the 12-hour run on the track, and World Bests for 100-mile Trail and 100 miles and 12-hours on a treadmill. 

He is also well-known for being his low carb, high-fat approach to training and racing nutrition aka his ketogenic diet. 

He is also a running coach and host of the podcast, Human Performance Outliers.

What records does Zach Bitter hold?

Zach Bitter has participated in more than 60 ultramarathons and claimed World Records in many events, including:

  • 100-mile trail record: On November 10, 2018, Bitter broke the 100-mile trail world record at the Tunnel Hill 100-mile race in Vienna, Illinois in 12:08:36.

    Bitter’s time was 24 minutes faster than the previous 100-mile trail world record set by Jonas Buud in 2010 at the Täby Extreme Challenge in Sweden.

    It was also 36 minutes faster than the previous 100-mile trail American record set by Ian Sharman at the Rocky Raccoon 100-mile race in 2011.
  • 100-mile track record: During the Six Days in the Dome event in Milwaukee, Wisconsin, on August 24, 2019, he set the His 100-mile track world record with 11 hours, 19 minutes and 13 seconds (a 6:48 miles) besting Oleg Kharitonov’s 2002 world record by almost 11 minutes, and was more than 20 minutes faster than his own American mark of 11:40:55.

    This record is now held by Sania Sorokin who broke it on April 26, 2021 with a time of 11:14:56 in Ashford, England.
  • 12-hour track record: After setting this record, he continued to run for another 40 minutes, setting the 12-hour distance world record by with 104.8 miles, an improvement of more than three miles over the previous record.

    In 2021, Sorokin also broke this record, continuing his 100-mile run to cover an additional 45 minutes to chase the 12-hour distance record. He covered 105.825 miles.
  • 100-mile treadmill record: On. May 16, 2020, Bitter broke the current 100-Mile treadmill world record of 12 hours and 32 minutes with 12 hours, 9 minutes, and 15 seconds averaging a pace of 7:18 per mile.

    He blasted the record set by Canadian Dave Proctor in May 2019 by 21:21.

    This record was broken by Taggert VanEtten on May 16, 2021 by running 100 miles on treadmill in a local pub in 11:32:05

How old is Zach Bitter?

Bitter is 35 years old.

Where does Zach Bitter live?

Bitter lives in Phoenix, Arizona.

Who is Zach Bitter’s wife?

Bitter is married to elite ultramarathoner Nicole Bitter, North American trail 100-mile record-holder with a time of 14:22. They reconnected while volunteering at a running camp is 2016.

They kept in touch and Bitter crewed for Nicole at the the North Face 50-miler in San Francisco in December 2016. 

“The rest is history,” Nicole told RunSpirited.com

The two moved in together in Phoenix and were married in 2018. 

Where did Zach Bitter go to college?

Bitter attended the University of Wisconsin – Stevens Point from 2005-2008 and was a member of the Track and Field and Cross Country teams. 

When did Zach Bitter start running?

Bitter began running in middle school, ran in high school, and college.  He ran his first ultramarathon in 2010. 

“At UW-SP, I learned that I seemed to get better as the distances got longer, so to me, ultra-running was a logic sport,” Bitter told OrangeMud. 

Related: How to make the leap from marathon to ultramarathon

What does Zach Bitter eat?

Bitter generally adopts an LCHF (Low Carb, High Fat) diet.

That means he trains and competes on minimal carbs. At times, carbs account for as little as 5 percent of his diet. Instead, Bitter eats a lot of animal products, especially on recovery days.

Bitter told Men’s Journal that on a recovery day he consumes a lot salmon, eggs, and red meat. If he’s doing a big training run, he reintroduces carbohydrates–calling them rocket fuel. 

“If I’m doing something really strenuous, carbs are an advantage from a training standpoint,” Bitter told Men’s Journal.

Here is what Bitter eats on average during a recovery day:

  • For breakfast, he eats eggs and bacon with some spinach.
  • For lunch he eats a heart salad such as a Cobb salad.
  • For dinner, Bitter eats something like a tri-tip steak.

Bitter explained on the Joe Rogan podcast that he periodizes his nutrition, so it varies throughout the year and according to his training. 

According to his blog, his typical daily intake ranges from 5 to 30 percent carbohydrates. He eats more animal products aka a ketogenic diet to support recovery after hard workouts, and maintain his fat-burning ability.

He eats more carb-dense foods on hard workout days and during races. 

Related: How to run far on a Keto diet

Why does Zach Bitter not eat carbs?

Bitter told Men’s Journal, “In high school and college, I had a whole-food type of approach to nutrition, like a lot of endurance athletes do.

At that time, most of the research you’d find was based on a high-carbohydrate diet, so I skewed my nutrition that way. My diet was clean, but probably 60 percent carbs. 

“Then, in 2010, I started participating in ultra-endurance events and noticed that things weren’t ideal—not being able to sleep consistently through the night, having big energy swings during the day, chronic inflammation in my ankles, things like that.

“I was at a crossroads. One option was to scale back on training, and that wasn’t necessarily something I wanted to do.

The other option was to look at what I could do nutritionally, and that’s when I met Jeff Volek, M.D., Ph.D., who’s been very influential in the high-fat approach, and I made the switch.” 

Eating low carbs has also made Bitter an efficient fat-burner.

It has been recorded that in Dr. Volek’s FASTER study, which looked at fat and carbohydrate metabolism in endurance athletes, Bitter’s results showed that at his peak he could burn 98 percent fat and 2 percent carbs. He maxed out at burning 1.57 grams of fat per minute, above the once-theorized ceiling of 1.0 g/min. 

This means Zach is using less fuel than his competitors, allowing him to run faster for longer.

Related article: How To Run 100 Miles – The Essential Guide

What does Zach Bitter eat during a race?

Bitter has been known to run great distances taking in only water. He ran 38 miles of the Western States trail in a little over eight hours on only water, electrolytes, and a couple bites of fruit at an aid station. 

Bitter won the national 100K title in 2014, running 6:30/mile pace for seven hours while consuming only 156 calories per hour.

“Fueling is a hassle,” Bitter has said, “and the less you have to do it, the better.”

Bitter uses 33Fuel’s chia energy gel, the world’s only truly ketogenic energy gel. The gel claims to be customizable, low carb and high in healthy fats to promote fat burning and adaptation.

What supplements does Zach Bitter take?

Bitter reportedly uses

  • omega 3 fish oil
  • glucosamine chondroitin
  • lactic acid buffer
  • magnesium
  • vitamin k12/D3
  • whole food multi vitamin
  • CoQ10
  • spirulina powder

What shoes does Zach Bitter wear?

Bitter wears Altra running shoes. He is sponsored by Altra. Some models he has worn include Escalante Racer, Superior 4.5, Provision 4 and Vanish. 

Does Zach Bitter design his own running clothes?

Bitter has partnered with Purpose Apparel to design a series of running and athletic apparel. It is made of hypermesh, “the lightest material of its kind,” he writes on his site. View the line here.

What treadmill does Zach Bitter use?

When Bitter set the 100-mile treadmill world record, he alternated between two NordicTrack X22i treadmills. He alternated because they timed out every couple hours. 

What podcast does Zach Bitter host?

Bitter hosts a podcast called Human Performance Outlier, in which he interviews an array of guests from athletes to experts who have pushed endurance limits or provide information ranging from nutrition to injury prevention to help others do so. 

What charity does Zach Bitter support?

Bitter supports the charity Fight For the Forgotten, an anti-bullying nonprofit in the U.S. that also helps people in oppressed countries internationally through water, land, and food projects. Click here to donate.

What is Zach Bitter’s training philosophy?

Bitter aims to train specifically for his event, tailoring his training to the elements he may see on race day including terrain and environmental conditions.

Bitter also tends to favor running negative splits, which he did when setting his 100-mile treadmill record. 

Is Zach Bitter a running coach?

Bitter is a running coach who focuses on both motivation and a science-based approach. He offers basic structure scheduling for athletes as well as personalized and event-specific training plans. 

Prior to making his career out of running and coaching, Bitter was a high school teacher, so he is adept at helping others learn. 

To learn more about Bitter and his coaching services, visit zachbitter.com

Whitney Heins
Whitney Heins is the founder of The Mother Runners and a VDOT-O2 certified running coach. She lives in Knoxville, TN with her two crazy, beautiful kids, pups, and husband. She is currently training to qualify for the 2024 US Olympic Trials marathon.

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