So far, so OK, with glycogen depletion runs

As I told you here, I am experimenting with glycogen depletion on my long runs. Why? Well, as Laura explained here, the theory goes that when you fuel during your long runs, you deprive your body of the ability to tap into fat stores for energy. And even the leanest of the lean have lots of fat stores from which to draw energy. Glycogen, on the other hand, runs out before too long.

So–if you’re running a marathon, it behooves you to tap into your fat stores for energy. This doesn’t mean that you don’t fuel in a marathon, or that you don’t fuel during any of your long runs leading up to a marathon. But if you can first teach your body to use fat for fuel, then hopefully you won’t hit a wall in a goal marathon.

When I first read about glycogen depletion long runs, I thought, “there’s no way I can do that.” But after checking in with some trusted sources–Jeff Guadette, Dr. Mark Cuccuzella, and Jason Karp–I became convinced it was worth a try. I’ve now done a 16 and an 18, both handled a bit differently, in a glycogen depleted state. Here’s how they went and where I go from here:

Anyone else out there trying this? Or does it sound insane? 



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  1. says

    I know a few people here in SA that do this for ultras and do it quite often myself. I believe it works really well and conditions the body to make better use of fat reserves. I’ve never done a study or experimented with this and just follow the trend blindly., but I believe it works.
    Johann recently posted..The Time is FlyingMy Profile

  2. says

    Do you have any links to studies or the original articles that outline the physiological process for this? I’m taking a Metabolic Adaptations to Exercise class this fall and will definately ask my professor about this (he’s a PhD in Kineseology/Exercise Science, has worked with Olympicans, is a research scientist and an ACSM fellow).

    Based on the basic information that I know about the metabolic process and how your body decides which energy systems to use, I’m a bit skeptical about this, which is why it would be helpful to get a scientific explanation. I also have some hypotheses that this might be detrimental and counterproductive but want to do more research before I start spewing out bad advice & info.

    Also wondering how you plan on determining if this theory is working for you? What are your benchmarks and goals, and how will you know if it’s this training method that is producing results versus others you might also be employing?

    I guess that’s a question for anyone else who does this, how do you know it works? Just curious about what you’re measuring.

    Interested to see more. Thanks for sharing.
    Michele recently posted..My Timberman race planMy Profile

  3. says

    My runner brother always thinks I’m crazy for how much fuel I take in on long runs. I can’t imagine running that far without something, though! Very interested to see where this takes you.
    Julie recently posted..The Cold ShowerMy Profile

  4. says

    I’ll leave the glycogen depleted runs to you, but this is very interesting stuff! Having majored in Exercise Physiology, this taps the inner nerd in me. I would love to see some scientific papers on this, if there are any. I’m NOT challenging you, so please don’t feel that way. I would just love to research this more! Thanks for posting!
    Meaghan recently posted..For the Love of Long Runs..My Profile

  5. says

    Hmmm…the logic and studies make sense, I actually believe in doing so every now and again. Training is all about manipulating variables and preparing the body.

    You are always pushing the envelope and trying new things-that’s kinda cool:)
    Adrienne recently posted..Paradigm ShiftMy Profile

  6. says

    I have read some articles on this and am wondering if it would have really helped me through my first marathon when I hit the wall. Great job making it through your long runs in that state especially the 18 miler. I haven’t been brave enough to try it yet!
    Christy @My Dirt Road Anthem recently posted..The WallMy Profile

  7. says

    I’ve accidentally done two recently 14 & 16 miles (forgot gels and they were early morning runs). I found the 14 mile (the first one to be harder) but I think that’s because my pace was a little faster than it should have been (right around 8-8:10) and by mile 12 I was literally starting to delirious look for yards with orange trees to steal one. The 16-miler was a different story. I lost track of time and was so worried about getting home in time for a meeting I could hardly notice how I felt…but I was very slow by the end and had to walk mile 16. But it was also wicked hot -so who knows which caused which. Since they weren’t intentional I’d like to try it more intentionally and see how it goes!
    Sheila recently posted..True Confession Thursday: Did I Really Say That?My Profile

  8. says

    I’m hoping I’m on the right track as I never eat anything before any of my runs. For the long run, I’ll take in some fuel (3 shot bloks every 4-5 miles) and water, but that’s it. The wheels certainly came off my bus on this past weekend’s 22-miler, but I think it was because of the 99% humidity and the fact that we were running pretty fast (still managed an 11-minute pace overall even after walking the final 4 miles).
    Carrie recently posted..Week Nine RUNdownMy Profile

  9. says

    Very interesting Amanda. I have found the same thing to be true, when I slow my pace down I can do my long runs with nothing but If I get anywhere close to my goal race pace, I am fine until the last 1/4 of the run and then it is ugly. Nice post, I am very intrigued by the concept as I have crashed in every marathon I have run and many articles I have read say it is because my body does not know how to burn fat.
    LisaM@RunWiki recently posted..Almost Wordless WednesdayMy Profile

  10. says

    Thank you for sharing your FIRSTHAND experience with this Amanda! Glycogen depletion is practiced frequently in CrossFit WOD’s by fasting up until a workout (even though they are much shorter in duration, but very intense). Same concept. I know Emz is a fan of this training too. I really like the concept and have used it for training in past months but my mileage has been much lower! Love hearing from you!
    Jess @ Blonde Ponytail recently posted..Outside My Comfort ZoneMy Profile

  11. says

    First of all, l love the multi-tasking of taping vlog while son is fishing!
    I never fuel on long runs. I eat a little something a few hours before then only take in water (and even do that sparingly based on where I can find water fountains!)
    It has worked pretty well for me though I’m considering some fuel runs in the future just to try something new!

  12. says

    First off you look so pretty! This is very interesting and as I hope to be heading towards marathon training someday soon….i may just have to try this.

  13. says

    That sounds intense. I have a 50 miler coming up and I’m wondering if this is something I should try. My morning runs 5-8 miles are on an empty stomach and I usually only drink water during. That would be like a mini test, right?


    Great video. Sounds like fun is being had in the background.
    Pavement Runner recently posted..Playlist Thursday: San Francisco FlavorMy Profile

  14. says

    i never eat before my long runs. but i make sure i fuel adequately during them and after them. i’ve never bonked on a training run either. it works for me. full disclosure – i have bonked (hit the wall) during a marathon but i went out too fast. if you go out too fast in the marathon, nothing can save you!
    Kristy recently posted..Live GreaterMy Profile

  15. says

    I only fuel on runs over 15. Everything else I go fuel-less even sometimes no water. I have read it’s good to do that in base training, but as you get closer to your race, to fuel bc you want your stomach to be acclimated to taking in on the run.
    Kristy (@KrisRunTri) recently posted..Liebster BlogMy Profile

  16. says

    I find this really interesting especially since I hate fueling during runs because my stomach is usually not happy. I rarely fuel before or during runs less then 14 miles (just water), but I think I’ll try this on some upcoming longer runs now just to see. Thanks for sharing the information and your experience with it.
    Beth @ Miles and Trials recently posted..Getting through a tough runMy Profile

  17. says


    Stay with is and have a cup of coffee before the morning run. although this goes against the modern conventional wisdom it is physiolologic truth…just like running barefoot to reduce impact :)


  18. says

    Very interesting!! (Love your video blogs by the way!) Do you change your nutrition the week prior? (Focus on more water, more carbs, sodium, etc all week?) Just wondering if there are any other lifestyle changes you make to help yourself get through a glycogen depleting run in advance!
    Kara recently posted..Long Run PrepMy Profile

  19. says

    I think there are so many little variations you can do for those glycogen depletion runs. I tend to eat before my longs runs and have for while now, but I recently started to cut back what I ate before. Also I have always limited my intake of fuels during the long runs in order to get my body used to running without fuel. So I guess there are a lot of little steps you can take to get your body ready to run without fuel. I think gradually stepping down is what has worked for me for now – I am not sure I could handle an 18 miler without fuel – it would definitely be a tough run! Also I haven’t noticed a huge drop in my pace for runs under 13 miles where I don’t fuel before or during. I am not sure if that is because my body is used to running about 13 miles or less without fuel before or during.
    J recently posted..Triple DoubleMy Profile