The Stages Your Body Go Through When You Fast

Previously, I wrote about Why Is The Lockdown A Great Time To Observe A Fast? This post, certainly, is an extension of that article.

It’s not for me to emphasize the value of a properly performed fast and what it can do to your body, mind, and soul (considering I ventured on a similar path myself a few days ago during the lockdown.) This path speaks for itself.

I track all my fasts on “Fasting Tracker”.

Nonetheless, whatever experiences one beholds under this fasting tree, the concept of “detachment” remains fundamental. Fasting of any kind is, therefore, a great way to “let go.”

Coming onto the central topic, this is exactly what happens to our body when we fast:

Stage 1: (0-2 hours)

Blood Sugar Rises

Right after you have begun your fast, you will feel pretty normal because your body is going through the process of breaking down glycogen. Your blood sugar will rise and your pancreas will release insulin to break down the glucose for energy and store the extra for later on.

Stage 2: (2-5 hours)

Blood Sugar Falls

Due to the insulin, the blood sugar will decrease to normal after the initial spike. It would not typically continue to climb because the insulin has been already delivered to the circulatory system after eating.

Stage 3: (5-8 hours)

Glycogen Reserves Drop

Feeling hungry yet? You probably might start feeling a few hunger pangs because your body is reminding you haven’t had anything for a while; however, you are not THAT hungry, actually.

At this stage, you would NOT starve to death or your muscles will not shrivel up. It is just your glycogen level that has begun to fall. Your body will digest your last food intake and then begin to use the energy it had previously stored.

Stage 4: (8-10 hours)


It is after 8 to 10 hours since your last meal that your body actually switches into the “fasting mode.” According to the research, gluconeogenesis is a metabolic pathway that results in the generation of glucose from the fat stored in your body instead of carbohydrates. Naturally, it’ll increase your calorie burning.

Stage 5: (10-12 hours)

Depletion of Glycogen

At this point, your glycogen reserves will wear out, or what we like to say– we feel “hangry”. Relax. Probably knowing that this is the time when you finally start burning fat will make you less irritable, motivated even.

Fat cells will release fat into your bloodstream where they also go to the liver and are used as an energy source. This is like tricking your body to burn fat instead of carbohydrates in order for it to function

Level 6: (12-18 hours)

Ketosis Stage

You finally arrive at this stage which is currently the most trending stage amongst the fitness enthusiasts. The glycogen is all used up and your liver starts converting fat into ketone- an alternate energy source. It is exactly why the ketosis stage is also called “the fat-burning stage.”

Another interesting fact is that at this stage, fewer inflammatory by-products are produced, therefore, it promotes heart, metabolism, and brain health.

Stage 7: (18-24 hours)

Fat Burning Stage

The longer you fast, the deeper into ketosis will you go. At this point, the energy supply from fat increases rapidly.


  • Ketones in the body rise.
  • Ketones will act up as a signaling molecule to inform the body of how to regulate metabolism in a “stressed” situation.
  • The body’s anti-inflammatory and rejuvenation processes are ready to begin their work.

Level 8: (24-48 hour)


It’s great if you could make it till this far. Autophagy literally means “self-devouring”. Cells begin to clean up their hours (just like most of us are doing to kill the time!) They remove unnecessary or disruptive components and allows recycling of cellular components.

So this is why it is important to fast in a pandemic crisis: During this period, the cells break down viruses, bacteria, and other unwanted components and use the energy to make newer parts. It is clearly significant for health, renewal, and survival.

The bottom line: The body turns it clock backward to create younger cells.

Level 9: (48-56 hours)

Growth Hormones Goes Up

This is where I ended my fast (48 hours, 45 minutes). Nevertheless, at this stage, the growth hormone is at a much higher level as compared to when it was before fasting. It helps to improve lean muscle mass and cardiovascular health.

Level 10: (56-72 hours)

Insulin Sensitivity

Great if you have diabetes because at this point the insulin level is at its lowest since you began your fast making you insulin sensitive. Lowering insulin levels have many benefits like activating autophagy and reducing inflammation.

Level 11: (72 hours later)

Immune Cells Regenerate or Survival Of The Fittest

After 72 hours of fasting, the body turns down the cellular survival pathways and recycle the warrior immune cells which were damaged when fighting against virus, bacterias and other non-essential components.

To fill the vacant spot, the body produces more immune cells at a rapid pace. It kickstarts the immune system regeneration and shifts cells to a state of renewal. Your immune system, thus, comes out stronger.

If this makes sense to you, there’s no reason why you shouldn’t experiment with one yourself. Although make sure you know the whys and hows of this process and you go slow.

You can also begin a long term fast by letting your body get used to the whole process. That’s where practicing intermittent fasting would benefit you. Read it here: Intermittent fasting: How good is it to skip breakfast?

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