My Experiment With Intermittent Fasting and Training on an Empty Stomach

eirik-garnas-carrying-bricks-organic-fitnessWhen I was just getting started with the whole health & fitness thing a long time ago, I bought into a lot of the conventional wisdom surrounding exercise and nutrition, and I, like most other people, had heard about the vital importance of eating an early breakfast. Even though I wasn’t hungry when I woke up in the morning, I remember “forcing down” canned tuna, eggs, whole grains, and other foods shortly after getting out of bed “to jump-start my metabolism” and “ensure optimal energy levels throughout the day”. It wasn’t until I started leaving conventional diet wisdom behind in favor of ancestral health principles, evolutionary biology, and the “real science” on nutrition that I realised how flawed this strategy was.

Intermittent fasting: The evolutionary norm?

From an evolutionary perspective, the idea that “breakfast [shortly after awakening] is the most important meal of the day” clearly doesn’t make sense. In the modern, industrialized world we have easy access to cheap and calorie-dense food at all times, but for hunter-gatherers and traditional, isolated people, the situation is very different. For many hunter-gatherers, most of the daily energy is taken in at 1-2 meals, often late in the day. Of course, they will eat leftovers from yesterday earlier in the day if there is any and snack on whatever fruit, tubers, and other foods they find, but in general, it’s safe to say that their meal pattern is very different from what we consider “normal” in westernized societies.  Over millions of years, the human genome was chosen by natural selection for ancestral natural environments. For our ancient ancestors, fluctuations in food availability/intake and intermittent periods of fasting were a natural part of life.

I might do a lengthy post on the science of intermittent fasting in the future, but today, I just wanted to put up a short description of what I’ve been doing lately. For the last couple of years, I’ve typically eaten my first meal of the day around 10 a.m., which is a couple of hours after I wake up, and my last meal of the day around 8-9 p.m. I feel this has worked well for me, but lately I figured I might mix things up a bit so I pushed the first meal 2-3 hours forward, to 12-1 p.m, basically shortening the feeding window to approximately 8 hours.

Since I’m used to eating a late breakfast, the change to now eating my first meal at around noon wasn’t as big as it is for people who come to this form of intermittent fasting after being used to eat breakfast early in the morning. However, the 2-3 hours do make a difference; the most apparent one being that I find it easier to stay lean. I also feel that my body responds well to having a longer break in between sessions of food intake.

I’ve always been an advocate of intermittent fasting for those who want to lose fat and/or have trouble keeping their body weight down without having to restrict calories. However, on the flip side, for someone who does a lot of heavy strength training and have trouble eating enough food to build muscle, intermittent fasting isn’t necessarily the way to go, as it can be hard to get as much calories as you need during the relatively short feeding window without stuffing yourself, choosing less than optimal sources of calories, and/or getting too little vegetables and fiber into your body.

Fasted training

I’ve also started doing fasted training in the morning. Prior to these last couple of weeks, I never did anything more strenuous than some low-intensity activities such as walking and light running on an empty stomach, as I had gotten it into my mind that I would get subpar results from doing heavy strength training, sprinting, etc. in a fasted state. I guess I haven’t been able to fully leave all of the conventional wisdom that was imprinted in me during my early years of strength and soccer training behind. Also, the fact that what I’ve been doing for the last couple of years (a balanced meal approximately 2 hours before a workout) seems to have worked for me have clearly kept me from making the leap to fasted training.

While I have to give fasted training some additional weeks before saying anything conclusive about the pros/cons, I can already say that I’m surprised by how well it works. I believed my energy levels would take a greater hit from not having a pre-workout meal, but as long as I eat well the day before, I seem to be doing just fine. One of the things I really like about fasted training is that I don’t have to worry about timing my day so that I get to eat a meal 2-3 hours before my workout. Fasted training also comes with several potential benefits related to protein synthesis, muscle growth, etc. that I might get into in a future post.

When we look at diet and exercise from an evolutionary perspective, it quickly makes sense why we are so well-adapted to train in a fasted state – and why fasted training is linked to many health benefits. Hunter-gatherers are very physically active, and they often hunt and gather on an empty stomach, typically early in the day. Since the ability to be physically active while in a fasted state was so essential to our ancient ancestors, it doesn’t come as a surprise that natural selection has equipped us with the capability to not only endure fasted training, but to perform well in a fasted state. However, we have to keep in mind that the type of physical activities performed by our Paleolithic ancestors differed from what a lot of us do in the gym today, and that training on an empty stomach obviously isn’t optimal for every type of activity/workout.

Needless to say, I’m a big proponent of a Paleolithic lifestyle, including Paleolithic-style diets and ancestral physical activity patterns. Occasional periods of fasting is a natural component of this way of living. In the future I might take the time to write a lengthy post on fasting, but in the meantime, there are plenty of great online resources you can check out (e.g.,

Do you have any experiences with intermittent fasting? Then I would like to hear from you in the comment section below.


  1. You are experimenting on yourself, always fun. I wanted to share 2 thoughts with you…

    1) I did IF for a year – last food 7pm, next would be noon but sometimes 1 or 2 pm if I was busy. Hunger at first, well tolerated after. Weight loss was not the goal, just metabolic flexibility. To set the stage -I eat clean, I’m lean, exercising for about 40 years. I LOVE exercising in the fasted state, both HIIT and HIT. I did my lipid profile at the start, then after a year – expecting amazing results – instead, my LDL shot up into a dangerous/treatment needed zone – no change in food quality or quantity. Stopped the IF, LDL back to normal. Monitor yourself – I’m told there may be a difference between how female and male metabolisms respond to fasting – I reached out to local and international researcher in fat metabolism – interesting, yes?

    2) From Dr.Bill Lagakos at “The poor, misunderstood calorie” – calories proper – explaining the importance of breakfast for circadian rhythm……. … September 27, 2014 …Conclusions …..
    Optimal: eat more when the tissue-specific circadian regulation of insulin sensitivity is high in muscle and low in adipose = earlier in the day. If circadian mismatched, FIX IT… these biohacks simply won’t work as well in that condition.
    Nutrient timing > CICO. Period… however, all of this is assuming a a plant-based, low net carb, whole foods template. And a protein-rich breakfast; not typical breakfast food crap.
    Don’t exacerbate afternoon diabetes with afternoon carbs. …. December 15, 2014…… Food: do more of it, earlier in the day. Phase advance. Kind of like avoiding artificial light a night or being young.night or being young. …..February 9, 2015 ….More on why breakfast in the morning, with light onset is important to avoid circadian desynchrony.

    • Hi, Newbie!

      1) Interesting results. As you hint, there is definitely a difference between males and females in terms of the response to intermittent fasting.

      2) I haven’t gone through all of the links you added. However, I have to say that I don’t agree with the notion that eating early in the day is as important as Lagakos suggests. Might do a post on this in the future where I discuss the science on nutrient timing and give you my perspective.

      Thanks for posting and sharing your experience.

  2. Jennifer says:

    I didn’t realize I was intermittent fasting but here’s what works for me.. I’ll start by mentioning that I’ve always been a morning person and have always preferred to work out in the morning before work rather than workout out after work; it just seems natural to me (workout and then shower for the day rather than shower twice a day), and having already done my workout before work sets me up for a less-stressful day. Morning workouts also help motivate me to get out of bed early and start my day. I’ve never had a problem with my energy level during a workout; in fact I always feel extra energized and focused after my workout.

    I’ve tried to workout after work but found that I’m sluggish; could be because I’ve already worked a long day but I think it’s more likely because I have a couple meals in my system — whereas morning workouts there’s been about a 10-hour window since my last meal.

    I can’t workout with anything at all in my stomach except for a cup of coffee. I have tried to eat something small (because of those same promises you mentioned “have fuel to burn for your workout”) but ended up not being able to make it through my workout because digesting while working out doesn’t work for me and I certainly don’t have time to wait for whatever to digest before working out.

    Another interesting thing I recently discovered is how meal timing affects hormonal balance. Although I don’t necessarily agree with all their nutrition suggestions The Nutrition Gurus hosted a free hour-long tutorial about how our hormones work (“weight gain after 40”). They recommend waiting about 11 hours between dinner and breakfast… There is a reason most people are not hungry when they first wake up and it really has a lot to do with the way our hormones work… and as it turns out that is what I’ve naturally been doing for years.

    I’m glad you’re experimenting; we all need to try different things to see what works best for us 🙂

    • Ditto, Jennifer. I hate training right after a meal, so if I train very early in the morning I like to do it on an empty stomach.

      Sadly, there is so much flawed conventional wisdom in the fitness community. When I first started out with strength training I remember eating a big post-workout meal before training and drinking a protein shake directly afterwards, regardless of whether I was hungry or not.

      I might do a post on nutrient timing and hormones in the future. Definitely an interesting topic. An evolutionary outlook is a great starting point for understanding all of this, as it is very important to look at the types of conditions our hormonal system, metabolism, etc. evolved under 🙂

  3. Interesting article. I have also experimented with fasted work outs. My experience has been mixed. I have found that working out (weight lifting, sprinting) in the morning w/o eating is okay. I am subjectively “strong.” However, working out in the afternoon while really hungry doesn’t work for me. I am weaker. I like the idea of a window in which one takes their meals. I have experimented with windows in various points of the day. I imagined that a window in which I stopped eating at 18:00 hours would be best for weight loss, but that hasn’t been supported by my experience. My experience has been that it is the length of the fast that determines the effect on my body mass.

    • Hi Galen!

      Welcome to the blog!

      Sounds like your experience with fasted training in the morning is the same as mine.

      When you say you do fasted training in the afternoon, do you mean that you fast through the night and don’t eat anything prior to your workout? If yes, no
      wonder your performance feels compromised.

      From an evolutionary perspective it makes sense to fast early in the day and have the feeding window later in the day. This is also the most practical approach to IF for most people.

  4. Love the article Erik and I’m looking forward to reading more from you on fasted training and your thoughts on IF and fasted training in the future.

    I have never been hungry in the mornings but on the other hand have always been hungry later in the day, from around 5 pm onwards. I was advised when I was trying to lose my excess weight to eat breakfast like a king but to decrease your food intake until you eat like a pauper at dinner. I tried this for quite a while but eating in this pattern didn’t work well for me. I found myself binging at night and beating myself up over it later… Instead I now eat both lighter and later in the morning and tend to eat my heavier meals later in the day about 1-2 hours after exercising and have found this eating and exercising pattern to work well for me so I’ve just stuck with this.

    On the weekdays, I wake up at 5 a.m. normally eat my first meal around 10 a.m., complete a relatively light 30-45 min. cardio, body weight or yoga session around 11:30 -12:00, have lunch around 1 p.m. and complete either a heavy strength/resistance training, or agility/balance/speed type session around 4:30 – 5:00 p.m. I eat dinner my final meal of the day after this around 8 p.m. I have a rule that I rest on the weekends maybe going for a walk or doing some yoga or taking a relaxing bike ride or recreational swimming… Typically I eat lighter on the weekends and usually just have 2 larger meals, brunch and dinner.

    I’m not sure if this exactly follows an IF plan or not but after after some reading and experimentation this eating and exercise plan seems to work well for me. My energy levels are good and I’m still gaining in terms of my fitness and health goals.

    • Thanks for sharing your experience, Alison!

      Sounds like you’ve landed on a good solution! Your current meal pattern/frequency looks a lot like I’ve been doing things for the last couple of years (Breakfast at 10, followed by training 2 hours later if possible, and last meal at around 8).

      Let me know if you need any advice/suggestions on how to reach your current health & fitness goals!

  5. I’ve been on IF for about 3 months. First started out with once a week 20 hr fast, recently doubled that about a month ago.

    The lean gains model of skipping breakfast and eating within an 8hr window appealed to my convenience but I noted that most of the studies were using the alternate day fasting model.

    My 60 year old out of shape dad has lost 1kg so far on the lean gains model though he’s not fully paleo and pretty sedentary.

    As for myself, I’ve dropped about 1 kg also while my leaness has remained unchanged IMO. That wasn’t my objective so I have added tubers of a regular basis on my non fasting days.

    Ive found that I can’t perform well on a empty stomach at the gym (mainly high reps calisthenics).

    Looking forward to an update on your IF experiment.

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