Biohack: Running 3 Marathons on Zero Calories


Early this morning I walked off the one mile track in Phoenix Arizona  where the Across the Years Ultra Race was taking place. Everybody who was running on the track with me was testing their limits to see how many miles they can rack up during 24, 48, 72 and 144 hours of running. My own interest was in being the first person to set a record for running multiple marathons using zero calories. I was successful in racking up just over 76 miles (almost three marathons) in less than 24 hours with no caloric intake during that time. I’m not suggesting that anyone try such a long fasted run, but I think the process of reaching this level of metabolic control might be interesting to others.

I made use of the following biohacking practices to pull off this run:

  • DNA Testing – Confirm marker for fat burning
  • Daily intermittent fasting averaging 19 hours daily for the last three months
  • Physiology Lab RQ (respiratory quotient) Testing – Confirm heart rate matches Niko Niko Pace and Phinney / Volek Number
  • Keeping Up Energy Levels – Caffeine, electrolytes and blood glucose / blood ketone testing

DNA Analysis

The PPARA gene was my primary concern when taking on an event that requires me to stay in a catabolic state. Half the population has it and I was fortunate enough to have two copies of  the ‘GG’ fat burning allele.

A common genotype in elite endurance athletes, GG individuals have higher levels of PPARA protein in their skeletal muscles on average. As PPARA turns on genes that shift our metabolism to more energy-e cient fat burning, this genotype is perfect for those undertaking endurance-oriented activities.

Via FitnessGenes



Daily Intermittent Fasting

Everyday I test my blood glucose and blood ketones as these are indicators of fat burning. What I have noticed from tracking daily fasting hours is that the longer I fasted each day the lower my blood glucose was and higher blood ketones. In my case 19 hours of fasting and 5 hours of eating seems to be optimal in terms of a comfortable daily practice with good blood numbers.

Staying with a low carb diet with macros of 78% fat, 11% protein and 11% carbohydrates appears to be where my blood ketones have peaked.

Physiology Lab RQ Testing

Most University Physiology Labs have the ability to do an RQ test (respiratory quotient). This test is a good way to learn the ratio of fuels you are burning. In my case I wanted to see confirmation that the heart rate ideal heart rate for me to run at matched across three different sources. The RQ test I did earlier this year at the University of New Mexico provided just that.

This above chart is a result of the RQ test that suggest if I keep my heart rate below 118 BPM I can keep my fat burn above 90%. The big unknown with running multiple fasted marathons was where is the other 10% going to come from later on in the race? The best part about this chart is that the peak fat burning heart rate matches up with two other popular formulas for maximum fat burn exercise.

  • Phinney and Volek – Suggest a 64% of VO2Max for maximum fat burn. My VO2Max heart rate peaked at 184 when tested at a physiology lab. 184 * .64 =117.76 or 118 BPM
  • Hiroaki Tanaka the author of “Slow Jogging” suggests the following formula:
    • 138 – (AGE / 2) =[ Niko Niko Heart Rate ]
    • In my case I get another match:
    • 138 – (40 / 2) = 118.

Having both general formulas match up with the RQ test gave me the confidence to train at a max heart rate of 118 for the last three months. This is the heart rate that I slow jogged the 100 mile fasted run at.

Keeping Up Energy Levels:

The final challenge in the race was to keep my energy levels at a suitable level for an entire day. While I did not take in any calories this still left room for water, electrolytes and caffeine. I took a home made magnesium, potassium and sodium solution ever 2 hours. I also took a “Sprint” caffeine tab mixed with l-theanine and B-Vitamins every 4 hours. I’ve found the cramping to be unbearable unless I continuously take the electrolyte mixture. Checking my glucose and ketone levels every two hours confirmed that I was running at the right pace to produce enough ketones for this event.

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  1. Mikey, this is amazing! What did the run feel like? How hard did it get mentally, and when did you start cramping? Did the electrolytes work quickly, or did it take hours for then to work. Great job!

  2. Hi Jeff,

    Thank your for the positive feedback and interest.

    I felt great for the first 12 hours (50 miles). I had a few higher effort loops and took my normal vitamins in the second half which wasn’t such a good idea. It messed with my stomach and started to disrupt my energy levels. I needed to rest for an hour to get my belly back to a stable state. I also got a little tired just before sunrise and took another 1.5 hour nap. The calf cramping started just after the second nap. Otherwise mentally I was very clear and positive with no real issues. I liked my setup for electrolytes every two hours and 50mg of caffeine every 4 hours.

  3. Christiaan Oosterveen

    Love this challenge! Great experiment!

    Now I am wondering what would you do to run energy wise if you have to run your fastest marathon possible.

    I am a Growth Hacker and I am hacking a sub3hr marathon from scratch with just 200 km of running experience. and 25 weeks of preparation.

    What would you suggest to figure out the best strategy energy wise?

    Would love to learn from you what tests I should do to figure out my ideal heart rate.

    At this moment I have been able to go from scratch to a 44 min 10k in just 5 weeks. My longest run in my life before starting was 16km in 1hr40m.

    Your story supports my thinking that it might be possible!

  4. Christiaan,

    What has been your training regiment to get so fast with so few miles? I assume it is HIIT based.

    My chart above Fat Utilization over heart rate is the best of both worlds compromise. It has me running at a heart rate of 145 BPM which is very comfortable, but still allows me to run a sub 8 minute mile. It requires fueling, but not much because I can still get 70% of my calories from fat. That heart rate happens to match MAF (Maximum Aerobic Function) so I would strive for MAF as a marathon pace. If that is too slow you can go another +10 over for race day, but it will take more fuel.

  5. Hi Mikey, I ran with you at Moab 240 that first night. I was wondering how your experiment would turn out — great job! I have a coworker I’m trying to help who always hits the wall several miles before the end of a marathon. I’m thinking running a few ultras will help his body to learn to burn fat more efficiently. But you’re showing us how much that paradigm can be pushed. Keep up the good work.

  6. Hi Mikey, this made truly excellent reading, especially as you also stayed ‘clear and positive’ during the run! That’s a feat in itself.

    Can you share with us the recipe for your home made magnesium, potassium and sodium solution? I’m presuming this is your electrolyte mix?


  7. Hi Tim,

    I buy the three ingredients for my electrolyte pill in bulk.

    – Pink Himalayan Salt
    – Bulk Supplements: Magnesium Citrate
    – Bulk Supplements: Potassium Citrate

    I mix equal parts of all three electrolytes in small container and use Size 0 Gel caps to scoop up and encapsulate the contents.

  8. Mikey,

    Met you at COLO 200, and you did some testing on us for fat-burning. I’ve enjoyed seeing your biohacking posts, a lot of interesting science behind it all! I’m particularly interested in the DNA analysis, and who did the testing (and test type) to confirm PPARA presence and the `GG` allele…

    Looking forward to more of your reports in the future!


  9. Hi Jake,

    Good to hear from you. I totally remember testing you at CO200.

    I would recommend going with 23andMe for DNA analysis right now. They do cover the PPARA gene and their pricing is quite good for the 600k SNPs they test for ($70). Send it to promethease after that for further analysis.

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