Home » Fasting and Autophagy: Everything you need to know

Fasting and Autophagy: Everything you need to know


Fasting and autophagy have become popular terms in modern health culture due to their links with longevity. We know that both can promote health, but many people still have more questions than answers.

Anyone interested in fasting has most likely heard of its links to autophagy, while anyone seeking autophagy will probably be lead towards fasting. Either way, they’re both intertwined and can work in synergy to promote wellbeing.

Although we don’t quite have it all figured out just yet; this article will give a clear and honest review of what we know so far. We will look at clinical data throughout, define some key terms and guide you through the world of using fasting to induce autophagy.

What is autophagy?

Autophagy is your body’s way of clearing out old, damaged cells. This is described perfectly by the name ‘autophagy’, which translates to ‘self-eating’.

The process of autophagy is a vital longevity mechanism that keeps your body free of damaged cells. It works by recycling and removing dysfunctional cells and replacing them with healthy new cells.

The body’s ability to remove malfunctioning cells and debris is vital to your existence. Without autophagy, the body would become dysfunctional and age rapidly. It would not be able to regenerate after experiencing life’s stressors.

It’s obvious why autophagy has been so strongly linked with longevity given the fact that it’s a self-regeneration process. Out with the old and in with the new.

Human cells perform autophagy

What is the link between fasting and autophagy?

Fasting is defined as ‘abstaining from some or all kinds of food or drink’. In the context of modern health, it usually means complete abstinence from all calorie containing food and beverages.

As fasting slowly starves the body of energy and nutrients, it forces the cells to look elsewhere for fuel sources. Without any remaining stored energy to burn, the body looks to digest old dysfunctional cells and converts them into energy for survival. This is when autophagy starts.

During a fast, the body will also start to break down fat for fuel in the absence of carbohydrate. Some of these fat cells will be converted into ketone bodies, which are used as a form of energy.

Research suggests that higher levels of ketones could stimulate autophagy. Reducing carbohydrate intake is the best way to raise ketone levels, and fasting is the ultimate carb restriction. No wonder it’s so heavily linked with autophagy.

Burn fat plate (fasting)

What are the benefits of autophagy?

Fasting and autophagy have been linked with numerous benefits. Refraining from food and allowing your system to ‘repair’, ‘reset’ and ‘regenerate’ can work wonders for a range of health markers.


Fasting is often touted as one of the best ways to increase lifespan. The main reason it’s held in such high regard is because it induces autophagy.

Recycling old damaged cells and replacing them with newer versions is clearly tied with longevity. You’re literally rejuvenating your body at the cellular level.

Cancer prevention

Since autophagy is the recycling of old broken cells, wouldn’t it make sense for the body to break down cancer cells? After all, they’re definitely surplus to requirements.

Well, according to some studies, that’s just what the body might do. Researchers are speculating that inducing autophagy through fasting is a potent way to starve and ultimately recycle cancer cells in order to preserve the body and create energy.

Despite research in this area being in its early stages, the signs are certainly promising.

Reduced risk of neurodegenerative disease

Growing evidence is showing the strong links between dysregulated autophagy and neurodegenerative diseases, such as Parkinson’s and Alzheimer’s. In fact, inducing autophagy is now being assessed as a preventative and treatment measure against the onset of these diseases. Amazing.

In the promising studies, they have found that autophagy is capable of reducing the amount of misfolded proteins within the cells. These proteins are viewed as the hallmark of most neurodegenerative diseases.

Conversely, dysregulated or lack of autophagy could cause these proteins to become rampant in the body, thus increasing disease risk. Unfortunately, our modern lifestyle promotes eating a carbohydrate rich diet without performing any fasting. No wonder these diseases are so prevalent.

Weight loss

Since fasting restricts calories, it should be no surprise that it’s strongly associated with weight loss. However, what’s more astonishing is the role that autophagy might play.

Recent studies have indicated that autophagy is strongly linked with metabolic health and dysregulation of this process could be the root cause of obesity, diabetes and other lifestyle driven diseases. In fact, inducing autophagy might be a way to reduce body weight by shedding excess damaged cells and proteins. Remarkable.

Improved heart health

In a 2017 paper, researchers shone a light on how autophagy might impact cardiovascular health. Upon review, they found that dysregulated autophagy may be connected to atherosclerosis and heart disease.

The review acknowledged that clearing out damaged heart cells may be a good way to reverse and prevent these heart conditions. Stimulating autophagy is a great way to clear out damaged cells, hence its link with heart health.

Reduced inflammation

Mounting research has shown a link between autophagy and the immune system. In fact, it may be a key component in keeping inflammatory diseases, such as Crohn’s and cystic fibrosis, at bay.

The paper states that ‘autophagy plays a critical role in inflammation by influencing inflammatory cells’. Modulating and disposing of these inflammatory cells could make autophagy a key therapeutic intervention for multiple chronic diseases.

Improved blood sugar regulation

Fasting is known as a great way to reduce blood sugar levels. By entirely removing carbohydrate intake, you give your blood sugar time to stabilize. In fact, intermittent fasting is widely viewed as an effective treatment for type 2 diabetes.

However, it’s more than just calorie restriction that makes fasting so effective. Fasting may also be a mechanism by which diabetes can be prevented, managed and potentially reversed.

Research coming out of the Journal of Cellular and Molecular Medicine looked at insulin producing cells in rats and humans. The study suggested that impaired autophagy can lead to reduced insulin sensitivity, which is a hallmark of diabetes. Conversely, making sure autophagy is firing on all cylinders may work to repair these cells and improve insulin signalling.

Autophagy health

Can fasting and autophagy be bad?

Too much of a good thing can often cause issues; fasting and autophagy is no different. The very essence of complete calorie restriction is a stressor on the body and the resulting autophagy is often a last-ditch survival mechanism.

Of course you can’t fast forever, so eventually you’ll need to eat in order to survive. Constant autophagy would also pose a problem, since at some point you will run out of cells to ingest and recycle. In essence, you need to give the body space to rebuild before you start breaking it down again.

On this basis, fasting and autophagy should be ‘pulsed’ in a dose dependant fashion. You first need to assess how long you’re able to safely fast without causing negative stress on the body, then you can analyse whether this is sufficient to induce autophagy.

Bad apple

How long should I fast for autophagy?

The literature on fasting for autophagy is still in its infancy, so estimates in humans can be hard to find. In addition, the length of time required to reduce insulin levels and deplete energy stores will depend entirely on your individual metabolism.

That being said; One trial looked at participants who ate their meals between 8am-2pm, often referred to as ‘early time restricted feeding’. It’s arguably the best human data we have, with the results showing that autophagy genes were expressed after 18 hours of fasting.

In another study, autophagy was measured in both mice and human cells following a longer period of fasting. It found that autophagy genes were upregulated in mouse cells after 48 hours, whereas they found minor changes in autophagy related genes after 4 days.

Based on the limited evidence we have so far, you should be looking to fast anywhere from 18 hours to 4 days (or more) in order to induce some level of autophagy. Keep in mind that the recycling of damaged cells should become upregulated over a longer time period, so it may take multiple days of fating to achieve ‘deep autophagy’.

Fasting and autophagy

Do you have to fast for autophagy?

Although fasting is often viewed as the best way to induce autophagy, it’s not the only way. In fact, there are a wide range of lifestyle choices that you can make to improve your chances of boosting autophagy on a daily basis.

When you’re not fasting, it might be worth considering including the following food and beverages in your diet. Each of these have been shown to increase autophagy:

  • Coffee
  • Turmeric
  • Onion
  • Green tea
  • Berries
  • Apples
  • Ginger
  • Ceylon cinnamon
  • Reishi mushrooms

Another way to promote autophagy through food is by limiting carb intake, or following a ‘keto’ diet. Since this dietary pattern significantly lowers insulin and blood sugar levels, it mimics fasting in a way that may induce autophagy. It will also speed up your transition into autophagy once you start your fast.

One more potentially potent method of stimulating autophagy is exercise. It will put enough stress on the body to trigger the mechanisms associated with cellular repair, and has been shown in studies to induce autophagy within peripheral tissues and in the brain.

Coffee for autophagy

How do you know if autophagy is happening?

Unfortunately it’s incredibly difficult to test for autophagy, so there is no concrete way of knowing if the process is happening in your body or not. It’s all a bit of guess work.

Despite the limitations in testing, there are some tell-tale signs you can look for during your fast that might signal autophagy:

  • Low blood glucose levels
  • Elevated ketone levels
  • Reduced appetite
  • Bad breath (associated with elevated ketone levels)
  • Weight loss

These symptoms have always been associated with medium to long-term fasting, even before the recent discovery of autophagy. Usually they will tend to show up after 16 hours of fasting and become more intense the longer you abstain from food. This works into the theory that autophagy becomes more profound the longer you fast.

Person fasting for autophagy

My anecdotal fasting and autophagy protocol

I personally believe that a small amount of autophagy can be achieved by performing a daily intermittent fast. I generally fast for 16-20 hours per day, and prefer to eat my calories in the early portion of the day, usually starting my fast around 4pm.

This is in line with the previously mentioned ‘early time restricted feeding’ study, which showed benefits after 18 hours of fasting when consuming your food early in the day.

I also follow a low carbohydrate diet that keeps blood glucose and insulin low, which also allows me to enter ketosis from time to time. I also regularly perform cardiovascular exercise in a fasted state, which I believe may combine the benefits of fasting and exercise to further induce my chances of autophagy.

Finally, I also eat a wide variety of plant foods, many of which have been strongly linked with autophagy. For example, I include turmeric in my diet every day.

The benefits I have observed in myself through this routine have been astonishing. Reduced appetite, improved body composition, reduced hair loss, improved vision and even younger looking skin have all been noticeable.

Whether these results are from fasting or autophagy (or both!) remain to be seen, but the results I have achieved confirm that I am on the right path.

Foods that induce autophagy


Fasting and autophagy go hand in hand. Both provide a host of health benefits that everyone should be looking to access, and together they might hold one of the keys to human longevity.

Since autophagy was only discovered in 2016, we are still waiting for further data to confirm just how crucial it is to human health. It’s difficult to design fasting protocols around autophagy because it’s just so difficult to measure.

The information in this article provides a breakdown of the best information we have so far. From this guide, you should be able to put together a basic fasting routine that may ultimately lead to enhanced autophagy.

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