Is 16-Hours Fasting Enough for Autophagy?

Did you know that autophagy and fasting can put our bodies through positive stress, which may bring many health benefits?

More and more people are supporting extended or intermittent fasting, arguing that we don’t need the typical three meals and in-between snacks a day to survive.

Moreover, many claim that humans can function perfectly even after prolonged periods without eating.

It’s also believed that fasting can trigger autophagy. Consequently, it allows our bodies to break down old cells to recycle and reuse some cellular components in order to operate more efficiently and help us feel better.

However, there are still many questions about whether 16-hour intermittent fasting is safe, how long we should fast, and whether it can actually promote our overall health by inducing autophagy.

Fortunately, you can find the answers to many of those questions here. Read on!

What Is Autophagy?


This term defines the physiological, natural process through which our cells feed on themselves, cleaning out old and damaged cells and reusing some parts.

Through autophagy, aged and damaged organelles, misfolded proteins, and pathogens are degraded and cleaned out, removing cell debris.

When this process begins, the autophagosome forms and fuses with a lysosome (organelle with enzymes capable of destroying or degrading molecules) as soon as it is fully enclosed.

As a result of both organelles’ fusion, the autolysosome is created. Here’s where cellular parts degrade, recycling and reusing some for cellular repair.

In this regard, autophagy removes damaged or dysfunctional cells to leave the healthier ones, which is key to cell homeostasis. Therefore, it has been linked to improved longevity, longer lifespan, and prevention of some conditions, including neurodegenerative diseases, cancer, and diabetes.

While autophagy can naturally start when the body suffers from infection or inflammation, we can also induce it through fasting, calorie restriction, and exercise.

Why Is Autophagy Important?

Autophagy is an indispensable mechanism for humans for multiple reasons. Here are some of them:

  • Autophagy plays a crucial role in cellular homeostasis, leading to healthier cells.
  • When autophagy declines or increases too much, it can cause abnormal cell growth or cell death.
  • This mechanism recycles damaged cell parts to use functioning or healthy cell components.
  • It removes nonfunctional cell components slowing performance.
  • Autophagy destroys pathogens that can damage cells, such as bacteria and viruses.
  • Problems with autophagy have been linked to cancer, as cell junk can lead to errors in cells’ genetic material or DNA, allowing cancer cells to form.

Furthermore, autophagy plays a vital role in how humans age, as it can result in the build-up of cellular junk parts or malfunctioning cells if it decreases.

Also Read:  16 hour vs. 12 hour fast

How Long Should We Fast to Induce Autophagy?

As mentioned, fasting is considered one of the best ways to stimulate autophagy, as caloric restriction or long periods without eating can cause stress in the body, initiating this process. However, many still wonder how long we should fast to trigger that response.

Essentially, how long we should fast to induce autophagy depends on our metabolism. Many claim that our bodies activate autophagy two or four days after fasting.

However, researchers believe that autophagy begins only when our glucose and insulin levels are greatly reduced.

Some doctors and scientists recommend fasting for 32-48 hours, explaining that 72-hour fast autophagy could push our bodies to the limit even though it’s possible.

Therefore, we should always seek professional medical help if we want to fast for autophagy or start a calorie-restriction diet regime.

When Does Autophagy Start?

Understanding the autophagy fasting timeline can be tricky because it may vary from person to person. However, some studies have suggested that the process begins after fasting for 24 hours, reaching its peak after 48 hours.

Is 16-Hours Fasting Enough to Trigger Autophagy?

Considering the abovementioned information, could fasting for 16 hours be enough to trigger autophagy? Again, it depends on different factors.

Our bodies won’t enter a starvation-induced autophagy phase if we only wait a few hours between meals. This process is activated when there’s low liver glycogen, which often occurs after fasting for 14-16 hours.

Some studies also suggest that autophagy occurs after 18 hours to four days of fasting, arguing that a 16-hour period isn’t effective enough.

However, there are really very few studies that measure autophagy and fasting in humans.

Moreover, there are other ways to stimulate the autophagy process without starving for days, including the following:

Intermittent Fasting

It’s a method that involves fasting or not eating any food for specific periods each day or week.

This diet regimen has different approaches or patterns depending on how long we fast or the method to reduce or restrict caloric intake. All of them can cause an increase in autophagy gene expression.

Calorie Restriction

With this method, instead of fasting to reduce our energy units, restricting calories limits them, forcing cells to go into an autophagy phase to make up for lost nutrients.


Exercising can also stimulate processes that increase autophagy-related proteins (ATGs)’ activity, triggering this response.

Also Read:  Fasting for 16 vs. 18 Hours

High-fat, low-carb Diet

Switching to this diet, popularly known as the ketogenic diet, can also induce autophagy, as it changes how our bodies burn energy.

If we reduce carbohydrates or sugar consumption, our bodies won’t get energy from there but will burn fat, which can promote autophagy.

Foods and Beverages that May Influence Autophagy


Even if we spend 16 hours fasting, autophagy can be influenced by other factors, including food.

Studies suggest that protein-based drinks could decrease autophagy activity. However, others show that some foods could stimulate this process, including the following:

  • Green tea
  • Coffee
  • Onions
  • Grape skin and red wine
  • Soybeans
  • Nuts
  • Berries
  • Apples
  • Milk Thistle
  • Tumeric

Some supplements might also help, as researchers have also found that spermidine-rich diets might also induce autophagy.

Can We Identify Sings of Autophagy?

Sings of Autophagy

If we start to fast for autophagy, there are some signs that can indicate if we have reached our goal or are close to it. The following are the most common:

  • Elevated ketones
  • Low insulin
  • Weight loss
  • Low blood glucose
  • Muscle loss
  • Reduced appetite
  • Skin health

Is Autophagy Good or Bad?

Although autophagy has been linked to many health benefits, it can be bad in some situations. Below are some important examples.


Autophagy is believed to prevent cancer development by eliminating many cancerous cells. However, some studies suggest that this mechanism may cause tumor cells to survive under stress for long periods, increasing the risks of tumor growth.

Cell Death

This mechanism removes damaged cell components, which is essential in cell death prevention.

Moreover, autophagy could promote cell death in people receiving chemotherapy treatment.

However, research has also suggested that different cells may react differently, and it could help cells survive in some cancers.

Neurodegenerative Diseases

Neuronal autophagy breaks down harmful proteins accumulated in the brain, creating a protective effect against neurodegenerative diseases such as Alzheimer’s and Parkinson’s.

However, this mechanism could facilitate certain proteins’ generation inside the nerve cell, causing cellular degeneration.


Autophagy can also kill some pathogens, reducing bacterial and viral infections.

However, research has also suggested that bacteria and viruses could also degrade this mechanism to replicate and spread throughout the body.

Final Thoughts: Is Fasting for Extended Periods Good to Induce Autophagy?

When it comes to inducing autophagy, fasting for long periods could help, allowing us to enjoy all the benefits that this mechanism brings to our bodies.

However, autophagy is not only key to generating healthy cells but may pose some risks in some cases.

Therefore, if you want to fast to initiate autophagy, seeking help from a medical expert is essential!

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