Zach Bitter on Low Carb Diets and Ultraendurance Running
Low-carb diets for endurance athletes still remain controversial and everyone has their own opinions and interpretations of the literature through the lens of their own biases. Me included :)
There are athletes out there crushing it using ketogenic diets in their overall strategy for optimizing performance, one of which I have become friends with over the years, Zach Bitter.
Zach Bitter is a wicked endurance athlete who has broken multiple World and American records throughout his career.
Notable Achievements:
Current 100 Mile World Record Holder (11 hours 19 minutes 13 seconds)
Current 12 Hour World Record Holder (104.88 miles)
9th Fastest Time Recorded on the historic JFK 50 Mile Course
Three-time National Champion (50 Mile ‘12 & ‘15 100km ‘14)
As far as I can tell, his diet includes a lot of ground beef and eggs, and not a lot of carbs. He’s appeared on Joe Rogan’s podcast twice (#1110 and #1392). So, go check out those episodes to learn more about Zach.
Below is a quick interview I grabbed with Zach to accompany an article I wrote for the Zero Fasting App but wanted to share it here in its entirety.
Kristi: What got you first introduced to a LC diet as a runner? And why did you think it was something you would want to try?
Zach: I first learned about low carb diets after listening to a podcast with Dr. Jeff Volek. After hearing his primer on it, and it’s possible applications with athletes, I dug in a bit deeper by reading Dr. Volek and Dr. Stephen Phinney’s books and some of their research. I began to find more folks interested in low carb, which led me to Dr. Dominic D’Agostino and many others. I was initially intrigued for a few reasons. One, I had just come off my first full season of ultramarathon training and racing and noticed my lifestyle did not seem sustainable. My sleep had been degrading, and while teaching full time along with training and racing, I noticed I had some pretty wild energy swings throughout the day. My training was going fine, perhaps due to doing most of it first thing in the morning, but I feared if I continued as is something would eventually degrade to the point it impacted performance and quality of life. Since I was new and excited about ultramarathons, I didn’t want to scale back on it if I could find an alternative solution. Looking back on it all, I probably got quite lucky that I came across low carb when I did, and that it worked as well for me as it ultimately did.
Kristi: Was the diet difficult to adapt to? Did your performance take a hit in the beginning and if so, how did you know this was something you wanted to endure?
Zach: I first dove in during my offseason, since I had learned that was ideal to make room for an adaptation phase. I spent approximately a month following a strict ketogenic version of low carb. I had a few days where I went past 50 grams of carbohydrate, but for the most part was quite strict. I also was completely sedentary during this time. My offseason usually has a fair bit of cross training, some strength emphasis, and when running feels exciting, easy, and motivating I will sprinkle in some unstructured runs. My first month was revealing to me. I almost immediately began sleeping straight through the night again. My training was a bit less predictable. I would have days where I would go out for an easy run and it would be exactly as it had when I was moderate to high carb. There were other days where I would stick to the easy effort, but be 1-2 minutes per mile slower than I would typically be at that intensity. After the first month, this normalized and all my easy paced runs were back to where they typically were at the start of a training block. Things got interesting as I began to structure and periodize my next training block. I follow a periodized training method that typically focuses on weakness and least specific intensities relative to goal race intensity, and progresses towards strengths and more goal race specific intensity. I noticed during the workouts that were moderate to high intensity, I felt a gear slow, especially if I grouped these type of sessions close to one another. This got me interested in the role of carbohydrate for someone with my lifestyle. I began to deviate some from strict keto into more of a low carb approach, where I would have a few more carbs around these moderate to high intensity sessions. It took about a year and a half to fine tune exactly the right amount that worked best for me, but once I had it dialed in enough it worked great. It felt like I had the benefits of low carb when I needed them, but it didn’t come at as much of a tradeoff on the moderate to intense days, since I was able to get my paces back down to where they were prior to going low carb. My typically base line range when in structured training is 100-150 grams of carbs per day. I do flex above and below those ranges at times when the workload is relatively high and when it is relatively low. This all is usually in the context of 15-20 hrs of training per week.
Kristi: Do you also eat LC during a long race? or is that when you use carbs strategically?
Zach: That is a good question, and it likely depends on how you look at it. I don’t eat low carb on race day, but from an energy usage standpoint I do. I will usually target up to 40 grams of carbs per hour during an ultramarathon. It isn’t uncommon that I will be burning 800-1000 calories per hour during these events, so even at 40 grams per hour, I am asking my body to burn a very high level of fat. The way I look at it, is at that intensity, I will still dip into my muscle glycogen. It just won’t be nearly as aggressive as it would have been when I was moderate to high carb. Since I will be dipping into my muscle glycogen at a low amount over the course of what at times can be an entire day, over time I can begin to dip far enough into this small fuel tank to where it benefits me to defend it with some exogenous carbohydrate. At approximately 40 grams, I can easily do this, and that has been low enough for me to also avoid digestive issues almost entirely. I like to look at it as being fat adapted enough to defend muscle glycogen on lower than average carb intake. For context, the most recent position paper on single day ultramarathon events, 50-70 grams is considered a good starting point for folks following a moderate carbohydrate diet.
Kristi: What is the biggest advantage to eating this way for you?
Zach: I am pretty focused on performance at this phase in my life, so I would lean towards that aspect of my approach. It likely plays out differently for each individual, but for me it allows me to feel even energy levels for those long running days, and the piece of mind that my nutrition isn’t going to be the cause of a digestive issue during an event that included 4-6 months of preparation. Outside of performance, although likely impactful on performance, it is incredibly advantageous to have reliable energy levels throughout the day and what I would consider great sleep quality. I also prefer this way of eating. Perhaps that is a byproduct of normalizing it over the past 10 years, but the foods that I include do happen to be the ones I crave and look forward to eating.
Where to find Zach Bitter:
Instagram: https://instagram.com/zachbitter
His Podcast: https://zachbitter.com/hpo
His Personal Website: https://zachbitter.com/
Twitter: https://twitter.com/zbitter