Burning More Fat While Running on Empty? (Part 1/4, Click Here)


5:45a.m. alarm sounds piercing everyone’s ears in the room.  I roll out of bed, onto the floor, and struggle just to put on my socks… and then shoes.  This looks probably like what I would imagine a giraffe on ice skates would be doing as well.  By 5:55a.m. everyone’s up because I have yet to finish putting on my long socks, usually superhero themed, and am now in some sort of weird yoga position, unintentionally, trying to get the last pull on the sock.

Before all of this mess occurred, and I began fumbling around the room…

What exactly happens during the night to my body as I sleep?  Better yet, what happens to all of us as we sleep and then wake up?  Upon waking should we eat or drink something?  Perhaps we should just get going…


Where to start?

First, I believe you should note what type of lifestyle you live and what type of training you perform week to week.  An elite athlete or lifter would not eat the same diet as someone who does quick bodyweight circuits 3x per week or goes for an occasional jog.  The overall goals and means to get to these goals are extremely different.

Are you taking in high carbs or high fats?  Where does your protein consumption fall? Are your meals spread throughout the day or in a narrow fastingtype window?  Do you track any of this and if so what’s your macro ratios?  And if not, you probably should be tracking if you want to hit certain goals and have yet to achieve them.

These are all important questions you should be thinking about as you read on. You can calculate your alleged Macros (HERE) though IIFYM.com but buyer beware, you will have to put your e-mail address in and they love e-mailing you.  I will say some good information is on the site if you are unsure or have never heard of macros or macro counting before.


  For an in-depth look at sleep, sleep cycles, hormones and responses during sleep, and much more: Click Here

According to a post from November 2015 from Jillian Michels she says you will not burn more fat on an empty stomach.  She states,”starving yourself before exercise can actually be detrimental to your body.”  She also sites a study published in the Strength and Conditioning Journal where they compared cyclists who ate before a workout vs. those who fasted and found the cyclist that fasted burned 10% of their calories from protein, including their own muscle mass.

However,  an article from Runtastic says it’s a bit more complicated than that.  “It is often wrongly assumed that without food intake, the body lacks the necessary carbohydrates and glucose (sugar) for a training session in the morning.”  Due to muscle glycogen (storage form of glucose molecules) stores, you body will have the ability to use these stores and free fatty acids circulating in the blood stream before you actually risk breaking down muscle protein into amino acids for use as energy.


(Pass the sugar please)

“Major changes in metabolism are known to occur as the glycogen supply dwindles; when glycogen storage in the liver is depleted, stored adipose tissue triglycerides are released into the circulation as fatty acids and glycerol.” From Nature Communications in 2013 where Izumida, Y. and colleagues experimented with glycogen changes in a fasted state.

They go on to say, “The released fatty acids are directly oxidized as an energy source by some tissues (liver and muscle), or are metabolized by the liver to ketone bodies for use by tissues, notably the brain that cannot utilize fatty acids, while the glycerol is converted by the liver into glucose (gluconeogenesis).”

T-Nation gets to the core of the breakdown though and simply says it’s not just the exercise routine you have to worry about.  A majority of studies have concluded that subjects will typically burn more fat in a fasted state than a non-fasted state during exercise.  The problem occurs as Paoli et al. study concluded, after exercise, fasted individuals end up using lipids (fat) less as fuel than the non-fasted individuals.  This was persistent for up to 24 hours post exercise.  This means the non-fasted group actually utilized fat better than the fasted group, post-exercise.


There’s so much more to understand about metabolism changes during sleep than what we are covering but let’s try and stay on topic as much as possible without writing a textbook.  After all that is the goal to give bite size posts for anyone to understand.

What we know happens during sleep under normal conditions:

  • Light, melatonin, hormones, and so much more play significant factors on our sleep cycles
    • Leptin (appetite suppressing hormone) secreted by adipose (fat) tissue and ghrelin (appetite stimulating hormone) secreted by the stomach both increase during sleep
    • Chronic over-sleeping or catching to few Z’s can have significant impact on these factors
  • Metabolic Rate Slows
    • That is to say, the amount of energy expenditure by the body decreases as we sleep
  • Repairs to the body occur during this time at a cellular level
  • Reduced glucose tolerance (elevated glucose) due to a reduction in insulin
    • Later in the night, glucose tolerance begins to improve and bring us back to a relative glucose (aka normal) level
  • Liver glycogen begins to be depleted and eventually will need free fatty acids to be used as fuel and possibly muscle glycogen if external fuel is not given to the body.


What Do We Do? 

“Most of us have some sort of meal within two hours before we go to bed and we rarely sleep for more than 8 hours, so if you get up and start training 10 or so hours after your last meal, your glycogen will be low, but it won’t be gone, so it could be argued that you’ll have just enough glycogen left to train hard, but low enough levels that you’ll burn more fat than normal to compensate for it.” Men’s Health Fitness Director Sean Hyson.

I believe this most important part of this article and series will always go back to the questions I asked you in the opener.  Knowing what type of diet you are adhering to and optimizing your performance can only occur if your energy balance (calories in vs. calories out) is going the way you want it to.

Would you drive a car without gas? Use your iPhone without charging it? Nope and nope.” – Jillian Michlels

I’ve done plenty of fasted workouts and plenty of non-fasted and a moderate amount fasted.  Key differences:

1.) I never do strength training fasted.  I tried a few times just to see what it felt like and it was terrible.  The weights felt heavy and I very quickly began to feel sluggish.  I quickly grabbed some fuel and finished my workout later on.

2.) I will occasionally wake up, usually 2x/week, and do a fasted cardio session.  For me, this means light bodyweight exercises, maybe a short run, and some yoga stability exercises.  I know my limits well and know if I start to feel any signs or symptoms of glycogen depletion, I will stop where I’m at and pick up another time.

3.) Indigestion:  A big reason fasted exercising is so tempting for me and why I tried it out in the first place, is I have had GERD in the past.  There’s nothing like trying to do a pull-up while holding back a major burp or major “heart burn” in your chest.  GERD pretty much take out any explosive or dynamic exercises or movements until it passes.  Simply, NOT FUN!

*Glycogen depletion symptoms can include: dizziness, weakness, and fatigue.


Professional Suggestions

Jillian Michels says eating a meal about 45 minutes to an hour before working out with carbohydrates and protein like greek yogurt and berries with crush walnuts or almond butter on whole grain toast and bananas.

Here are tips from Runtastic article if you decide to work out fasted so you don’t tear through the muscle glycogen stores and circulating free fatty acids:

  • Stick to low intensity pace jog/runs
    • Depending on fitness level, the run should only last between 40-60 minutes.
  • Stay away interval training or other methods of high-intensity training methods as these will burn through the stores faster.
  • Drink a glass of water before your run.


Final Word

Lastly, I want to strongly urge you to research any ideas you’re wanting to undertake.  Just because you see something posted on a timeline or from a fitness magazine, doesn’t make it true.  This is especially true when professional bodybuilders or others like them give advice.

I’m not condoning or saying all use performance enhancing agents, but some do and their bodies do not apply to the “normal” standards.  For example, they may do fasted cardio and have a completely different response.  I will do my best to give you the whole story but I still thin you should do your own research and ask around before making a final decision.  As always, send us your questions and thoughts because that’s why we are here.

Next Week:  

We take a deeper dive into fasting for ketosis and what exactly ketosis means.  Is this the new paleo or Atkins?  Will this be another fad or around to stay?

What are your thoughts?  Have you ever went into a workout fasted?  Drop us a comment and let’s get this convo going!


1.) Sharma, S., & Kavuru, M. (2010). Sleep and Metabolism: An Overview. International Journal of Endocrinology, 2010, 270832. http://doi.org/10.1155/2010/270832
3.) RUNNING & FITNESS • 19.04.2016 The 3 Biggest Myths About Running in the Morning on an Empty Stomach.
4.) Knutson, K. L. (2007). Impact of sleep and sleep loss on glucose homeostasis and appetite regulation. Sleep Medicine Clinics, 2(2), 187–197. http://doi.org/10.1016/j.jsmc.2007.03.004
5.) Scharf, M. T., Naidoo, N., Zimmerman, J. E., & Pack, A. I. (2008). The energy hypothesis of sleep revisited. Progress in Neurobiology, 86(3), 264–280. http://doi.org/10.1016/j.pneurobio.2008.08.003
6.) Petit, J.-M., Burlet-Godinot, S., Magistretti, P. J., & Allaman, I. (2015). Glycogen metabolism and the homeostatic regulation of sleep. Metabolic Brain Disease, 30(1), 263–279. http://doi.org/10.1007/s11011-014-9629-x
7.) Ip, M., & Mokhlesi, B. (2007). Sleep and Glucose Intolerance/Diabetes Mellitus. Sleep Medicine Clinics, 2(1), 19–29. http://doi.org/10.1016/j.jsmc.2006.12.002
8.) Izumida, Y., Yahagi, N., Takeuchi, Y., Nishi, M., Shikama, A., Takarada, A., … Shimano, H. (2013). Glycogen shortage during fasting triggers liver–brain–adipose neurocircuitry to facilitate fat utilization. Nature Communications, 4, 2316. http://doi.org/10.1038/ncomms3316

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