Working Out Fasted

I haven't talked much about this in a while, but on the heals of yesterday's post on fasting, Andy left a comment referencing a post by Rusty Moore of Fitness Black Book.

Fasted Workouts and Fasted Cardio vs EPOC – For Fat Loss

For the longest time, I didn't understand why I had more energy after fasting. I have my most productive hardcore workouts after fasting for 5-18 hours. If I ate anything in that 4-5 hour window before training, the workouts just weren't as intense. Ori Hofmekler explained where this "hidden" energy source came from…the Sympathetic Nervous System (SNS).

Go over and read more about the SNS.

As readers know, I have been working out fasted (18-30 hours) for a bit more than a year, now. I can't imagine doing it any other way. As an added benefit, take a cold plunge or sit in a totally cold bathtub after the workout, for as long as you can stand (in the summer, I somtimes remain in the 50ish degree water for 10 minutes). Then, don't eat until you're actually hungry, which, for me, is usually a couple of hours after the workout.

Richard Nikoley

I'm Richard Nikoley. Free The Animal began in 2003 and as of 2021, contains 5,000 posts. I blog what I wish...from health, diet, and food to travel and lifestyle; to politics, social antagonism, expat-living location and time independent—while you sleep—income. I celebrate the audacity and hubris to live by your own exclusive authority and take your own chances. Read More


  1. Jim on February 3, 2009 at 11:17


    I have been following your blog for months now, and enjoy it. I got into all of this through crossfit. I've read The Paleo Diet, and also The Paleo Diet for athletes, and have DABBLED in the slightest way with fasting. Usually that's just skipping breakfast, which for me is a big deal, but I know it doesn't really count. I keep coming to the same question. I recall the paleo diet for athletes saying that in an effort to absorb nutrients (glycogen?) in the post-workout window, certain drinks (glutamine) are ok to get it in. I asked Robb Wolf about that, and he said yes, although not as good as salmon and sweet potatoes. No argument here. My question is this: how do you reconcile the only eating when hungry afterwards with my understanding of the post workout window for nutrient absorption? I remember reading that 3 hours after the workout, you would absorb half as much from your food as within that initial half hour window. Feel free to paraphrase this or post any part, this has been my biggest conflict in information to date.

    p.s. I made an AWESOME paleo mexican pork green chili for superbowl. if you're interested, let me know, it's easy, it's crockpot, it's outstanding. Scraped the marrow out and mixed it in!


  2. Rusty - Fitness Black Book on February 3, 2009 at 13:15


    Thanks for the reference to my blog post. I really enjoy what you are doing here. It is cool that you are laying out your exact path to go from overweight to getting in amazing shape. There are so many people with a lot of weight to lose, that this will be an outstanding resource for them.

    Thanks for "improving the Internet" with you blog. We need more people like you who genuinely want to help others.

    Have a great one!


  3. Keith Norris on February 3, 2009 at 11:36

    I totally agree with working out in a fasted state. My norm is to workout 10 — 12 hours fasted, and on the weekends, I'll push it to 16 — 20 hours and even longer. I simply cannot hit the hyper-intensity I shoot for in each session until at least 6-hours post-feeding.

    It is my understanding (via the work of Dr. Mauro DiPasquale)– and my own empirical experience — that the "optimum post-workout feeding window" is an antiquated notion. Your glycogen stores will replenish just fine in due time (6-ish hours or so) to the same point as would be if you'd replenished within that "window". The downside to "replenishing" is the down regulation both of GH response and positive gene signaling. Not to mention the lost fat-burning opportunity. Now, that's just my 2-cents — Richard may have other ideas 🙂

  4. Richard Nikoley on February 3, 2009 at 11:44


    Here again is an issue I have not delved into that much. What I do know is that if I go 24 hrs fasted and check my blood sugar, it's at about 85. Then, if I go workout and test after, it's 105 – 110. Others have had similar results. See here:

    So, my approach has been informed by that (wait long enough for BG to come back down) and also in observing that many predator animals don't consume their prey right away (cats will often store it in a tree, for instance). As far as nutrient absorption, I just don't know. Paleo is high nutrition in any case, and, maybe it's better to be "nutrient deficient" in that window for better gene expression.

    Also, even if I've been fasting for 30+ hours, I have no desire whatsoever for food after a workout, and that sometimes goes for several hours (I''ve gone as long as six hours before eating).

    Just experimenting on myself and reporting results.

  5. Richard Nikoley on February 3, 2009 at 11:47

    I agree with you 100%, Keith (note my prior comment in resp to Jim). Above all, why in the world would I want to force food after a workout when my body isn't even hungry for it?

    The GH, gene expression, and fat burn are the best reasons, however.

  6. billy-jay on February 3, 2009 at 20:50

    Regarding the chili:

    Yes, very interested.

  7. Richard Nikoley on February 3, 2009 at 16:32


    Though I focus more on the diet aspect, I'm a big fan of Chris Highcock, and I've seen lots of guys I respect referencing you.

    I've hit your blog from time-to-time and plan to feature more of what you're doing here.

    I've added you to my — hard to get on 🙂 — blogroll. You really do good work and that outta be recognized far & wide.


  8. Chris H on February 4, 2009 at 13:43

    thanks for the kind words Richard.

  9. Andy on February 4, 2009 at 20:48

    Thanks for the nod, Richard, and keep up the good work.

  10. Simon Boyce on August 7, 2009 at 12:50

    Hi: thanks for your blog. I’ve been using the Fast-5 IF plan to try to lose some fat. But I’m still curious about the effects of working out in a fasted state. Wondered what you make of this – – and especially what is says about fasted resistance training and muscle damage… Thanks for any input. Simon

    • Richard Nikoley on August 7, 2009 at 14:52

      I’ll look more later, but I can never take stuff like this seriously:

      “Skipping Breakfast = Not Too Brilliant”

      Oh, so we should eat when not hungry?

      These people need to get out of the lab and start behaving like wild animals. I’ve been working out fasted from 18-36 hours for almost 2 years. In that time, I have increased strength 2, 3, and in some areas, 4 times.

      Very tough for me to take research seriously when it violates the principle of the wild animal right off the bat.

  11. jon on August 8, 2009 at 11:57

    Very true Richard. You don’t see wild animals like tigers and lions eating breakfast and than hunting do ya? they workout fasted all the time and the results speak for themselves. tigers and lions have much more muscle mass than any human can dream of.

  12. Andrew on October 22, 2009 at 12:30

    Hi Richard. Great Blog. You make a reference to Ori Hofmekler, he also says that we must eat within 45mins of a workout. I know Brad Pillon disagrees, from what I understand Brad says it doesn’t matter in you don’t eat after a training session. Whats your take?

    • Richard Nikoley on October 22, 2009 at 12:55

      Actually, it was the person I was quoting who made the reference.

      At any rate, I don’t think there is the slightest importance in whether you eat any time soon before or after a workout. I have often done a 10am or so workout fasted overnight or longer and kept fasting until dinner.

      This is all motivated by sugar addiction. Once people become fat burners it’s easy to see the whole rest of the world as addicts. And addicts always have all sorts of rationalizations and excuses to justify their addiction.

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