What Happens To Your Body During Fasting? 

 August 27, 2020

There a few set stages of intermittent fasting, each one having its own cascade of health benefits.

Between 6 and 24 hours, insulin levels in the body begin to fall as glucagon (a hormone formed in the pancreas which promotes breaking down glycogen to glucose in the liver) rises. As this happens, the body starts using up its stored glucose.

At the 6-hour mark specifically, the digestive system slows allowing the gut an opportunity to rest. This is very important for favorably altering the gut microbiome and strengthening the gut’s barrier lining.

Once 24 hours have passed, the body will start making new glucose from non-carb precursors. At this time, Human Growth Hormone (HGH) starts to rise and the process of autophagy begins.

A quick note on Autophagy…

Autophagy, according to Mayo Clinic is “a way for cells to break down macromolecules, such as protein and fat, into their component parts to be used in cell processes.”

If you want to know more about autophagy, visit the “Autophagy – Your Body’s Anti-Aging, Extreme Cleaning Team!” Blog post on our website.

Back to stages of fasting.

Many people worry at this point that such an intense fast will cause muscle loss. According to Span Health and many other resources, this is simply not true. Why would the body use muscle tissue when there is an abundance of stored energy in glycogen and fat!

When fasting goes longer than 48 hours (2 whole days… yikes!), stored fat becomes metabolized which now means that it can be used by your body for fuel, and ketosis begins.

Ketosis, according to Mayo Clinic, “occurs when you don’t have enough sugar for energy, so your body breaks down stored fat, causing ketones to build up in your body.” Ketones are efficient, low inflammation fuel sources that promote the release of what I like to call, “Miracle Grow for the Brain” but more formally known as brain-derived neurotrophic factor. According to Span Health, “BDNF helps brain cells grow and repair, and protects them against cellular stress.” Essentially, at this point, the body begins using fat instead of glucose as it’s main energy source.

At 72 hours, and for our purposes, the longest stint of the fast, autophagy stimulates immune system rejuvenation. This happens through the degradation of old immune cells and the creation of new ones!

Want to try fasting? Certainly don’t be disheartened when it’s difficult at first. However, by understanding what is going on in your body during each stage of fasting will be motivational for you in sticking to it!

An easy way to begin is simply by eliminating any food intake 2-3 hours prior to going to bed at night. Just by doing this, you are allowing your body to work on restorative processes during the night instead of digestion.

Have questions? We’re here to help! Contact a Tiger Representative today to discuss the benefits of fasting with a free consult.


  1. Stages Of Intermittent Fasting
  2. Healthy Lifestyle – Mayo Clinic
  3. How Fat Stores Provide An Energy Source – Mayo Clinic