The Real Reason Fasting Burns Fat (Activates Fat Burning Enzymes)


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The Real Reason Fasting Burns Fat (Activates Fat Burning Enzymes) – Thomas DeLauer

Norepinephrine and Epinephrine

Adrenaline is released from the adrenal cortex & goes through the bloodstream to affect numerous tissues in the body

Noradrenaline is released from the nerve terminals and is the main neurotransmitter of the sympathetic nerves in the cardiovascular system

These two play a primary role in the breakdown of fat by binding to the beta-1 and 2 receptors in the body, which increases cAMP levels which in turn increases fat breakdown

The nervous system sends norepinephrine to the fat cells, making them break down body fat into free fatty acids that can be burned for energy (1,2)

Hormone Sensitive Lipase

Fasting increases the activation of hormone sensitive lipase
Activating hormone sensitive lipase initiates lipolysis, the breaking down of triacylglycerols into free fatty acids and glycerol (3)


Fasting also increases glucagon levels, which breaks down fat – glucagon is a hormone that acts directly opposite to insulin (the pancreas secretes it in an effort to raise blood sugar levels)

While insulin stores carbs and builds fat, glucagon is responsible for breaking down stored carbs and fats and releasing them so your body can use them for energy (4)

How They All Work Together

The only site for regulation of fatty acid oxidation is at the level of hormone-sensitive lipase in adipose tissue

Under fasting conditions, with minimal insulin in the blood, glucagon promotes formation of the active form of hormone-sensitive lipase

When epinephrine is present, it further actives hormone-sensitive lipase, increasing the hydrolysis of triglycerides to produce free fatty acids (FFA) and glycerol

The glycerol is carried to the liver, where it enters gluconeogenesis, while the FFA are carried on serum albumin to the tissues where they are catabolized for energy

The liver uses some of the energy from fat mobilization to support gluconeogenesis (5)


Ketone Production: Burn Fat Instead of Sugar

Fasting shifts your metabolism from burning sugar to burning fat – begins to break down triglycerides in the form of ketones


1) Zauner C , et al. (n.d.). Resting energy expenditure in short-term starvation is increased as a result of an increase in serum norepinephrine. – PubMed – NCBI. Retrieved from

2) Jensen MD , et al. (n.d.). Lipolysis during fasting. Decreased suppression by insulin and increased stimulation by epinephrine. – PubMed – NCBI. Retrieved from

3) Sztalryd C and Kraemer FB. (n.d.). Regulation of hormone-sensitive lipase during fasting. – PubMed – NCBI. Retrieved from

4) Marliss EB , et al. (n.d.). Glucagon levels and metabolic effects in fasting man. – PubMed – NCBI. Retrieved from

5) Hormone-sensitive lipase – an overview | ScienceDirect Topics. (n.d.). Retrieved from

6) Adrenalin and Noradrenalin The ‘Dynamic Duo? (2015, April 9). Retrieved from


  1. Thomas, you should make some videos where you take some average people and apply your advice to them, showing a before and after. You're clearly on TRT, which means you're a lot more anabolic than normal people. So I think it would be interesting to see some before and after videos of what the average person could expect from taking your advice.

  2. A year or so ago I had adrenal fatigue but eventually I got out of it through lots of rest supplementation and cutting out caffeine I recently tried intermittent fasting and had great success losing about 12 lb but after that the adrenal fatigue seems to have come back and I'm wondering if that is due to the intermittent fasting having an effect on adrenals

  3. I have been fasting since October 2015, fast 17 hours and have a eating window of 7 hours. With training in the gym and some cardio now and then I have lost 187 lbs. Im eating three times every day, a lunch, a snack and a dinner.

  4. hey thomas, what is the main diffrence between niacin with flush, and niacinamid without the flush?
    is the flush itself, effectiv or important for the overall effect of vitamin B3? or is vitamin B3 without the flush, as effective in terms of health, metabolism etc as the flush-form?

    i mean with the flush, you got the feeling to do something ok, but i mean specific if it increase the effect like for example how B3 fights fatique, or fat metabolism?

  5. Like reading a book to go to sleep. Way too technical, are you reading this or do you KNOW it? I dont want to know this deep biochemistry, just tell me what works. I already thankfully know that fasting works. Whew.

  6. Hey so I just turned 15 and I'm trying to get a layer of body fat off of me. I have a decent amount of muscle on me already, with abs barely starting to show, but I can't seem to get them to pop through the fat. I want to start intermittent fasting, but I'm not sure how I should start. I am trying to do a 16-8 fast starting the 16 hours at 9pm, and eating at 1pm. I'm 15 so I live with my mom and I would like to know what kinds of foods I should eat and when I should eat them, I will buy the right foods so I can get leaner. It's getting close to summer so I want to get leaner, but I also feel like I want to gain muscle. Right now I'm at a point where I don't look bad without a shirt, but I want to look better than I do, I'm not really in a position to start bulking, because of the fat levels, so I would just like to know what kinds of things I could do to lose some more fat, while keeping muscle/ and or growing it a tiny bit. I just need some suggestions, thanks!


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