Luisa Torres, PhD
Luisa is a science communications manager at LifeOmic and neuroscientist and science writer covering topics related to aging, metabolism, and brain health.

Luisa Torres, PhD
Luisa is a science communications manager at LifeOmic and neuroscientist and science writer covering topics related to aging, metabolism, and brain health.


 

 If you have been practicing intermittent fasting for a while, you might have heard that autophagy is one of its many benefits. But what is it and why is it important for your health? 

What you’ll find in this article:

What is it? | How does it happen in your body? | mTOR and AMPK | The effect of age  | How long do I need to fast to reach it ? | Intermittent fasting and exercise turn it on | Foods that induce it | Signs your cells are increasing autophagy

* Illustrations by Tori Rogers.

What is autophagy?

Autophagy is a vital process our cells do for keeping themselves working properly. It involves packaging damaged cell components and transporting them to a recycling plant within the cell called the lysosome. There, damaged cell parts are broken down and reused.

Your cells maintain low levels of autophagy all the time, but they ramp it up when nutrients are low, or when there is increased demand for energy, such as when you’re fasting or working out.  

When you fast or exercise, your body can remove old components or turn them into things your cells can use. This gives you sugars and other building blocks that can power you through a fast or a workout. 

How does autophagy occur?

When your cells are ready for recycling,  3 things occur:

  1. A cup-shaped structure known as the phagophore begins to form around damaged components cartoon representation of the phagophore, the structure that forms around the cell parts to be recycled during autophagy.
  2. The edges of the phagophore extend and fuse, forming a new structure known as the autophagosome. This is the ‘recycling bin’ that will contain the damaged material.
  3. cartoon representation of the autophagosome, the structure that forms when the ends of the phagophore extend and fuse. this occurs during autophagy.The autophagosome fuses directly with a lysosome, (the cell’s recycling plant) which contains enzymes known as acid hydrolases that can digest old and damaged cell parts. This process generates sugars, amino acids, and fatty acids that cells can repurpose, and it gets rid of dangerous things that can cause disease, such as faulty proteins and even bacteria and viruses.

cartoon representation of the autophagosome fusing with a lysosome. This occurs during autophagy.

Autophagy can be ramped up and decreased as needed

mTOR (mammalian target of rapamycin) is a protein that normally prevents cellular recycling It becomes active when you eat and nutrients are plentiful. However, when you go without eating for several hours, a protein known as AMPK (5′ AMP-activated protein kinase) turns off mTOR and signals your cells to go into self-protective mode. This activates several proteins, including those known as autophagy‐related genes, which initiate autophagy by helping gather damaged cell parts and fusing them to the lysosome to be broken down. 

Animal studies show that cellular recycling might reverse the effect of aging on health. For example,  restricting calories in fruit flies increases their lifespan and restricting calories in rodents consistently improves their health. These effects seem to be due at least in part to putting the breaks on mTOR and activating autophagy. 

The effect of age 

 Autophagy becomes less efficient as you age. This causes your cells to accumulate damage they’re unable to repair, which is may lead to Alzheimer’s, Parkinson’s disease, and cancer.

Reduced autophagy causes premature aging and shortens the lifespan of many animals, from worms to mice to humans. Since mTOR puts the brakes on autophagy and its levels go up during aging, scientists think that increased mTOR might be the link between aging and reduced autophagy. AMPK also decreases during aging. Decreased AMPK might act in concert with mTOR to suppress autophagy in aged cells.

How long do I need to fast to see increased autophagy in my cells?

After 16 hours of fasting, neurons switch from using glucose to using ketones as their primary energy source. Ketones have been shown to promote autophagy in neurons. Therefore, it’s possible neurons ramp up their recycling mechanisms 16 hours into a fast.

A 2019 study with 11 overweight adults who only ate between 8 am and 2 pm showed increased markers of autophagy in their blood after fasting for around 18 hours, compared to control participants who only fasted for 12 hours. A second study detected autophagy  in human neutrophils starting at 24 hours of fasting.  In a third study, skeletal muscle biopsies of healthy male volunteers who fasted for 72 hours showed reduced mTOR and increased autophagy.

Autophagy increases throughout your fast. Be sure to fast for at least 16-18 hours per day to see the benefits of cellular recycling.

There are at least 2 things you can do to help your cells clean themselves up: High-intensity exercise and intermittent fasting.

Intermittent fasting and exercise increase autophagy

Intermittent fasting is not the only way to enhance the ability of your cells to recycle old components. American scientist Beth Levine showed that some of the known benefits of exercise for overall health have to do with increased autophagy. For example, autophagy induced by exercise delays the progression of heart disease by giving the heart better quality cell parts and reducing oxidative damage.

A cartoon representation on the effects of exercise on the autophagy. An exercise character high-fives an AMPK character with a 'recycling'facility in the background.
Physical activity, just like fasting, inactivates mTOR and activates AMPK.

High-intensity exercise encourages your cells to recycle

Exercise, just like fasting, inactivates mTOR, which increases autophagy in many tissues. Exercise mimics the effects of going without food for an extended period: It activates AMPK as well as autophagy-related genes and proteins. 

In mice, endurance exercise increases autophagy in the heart, liver, pancreas, fat tissue, and brain. In humans, autophagy increases during high intensity exercise, including marathon running and cycling.

Foods that turn on the recycling button

In general, your cells need a low-nutrient environment to increase their self-cleaning mechanisms. This ideal environment is usually achieved through intermittent fasting and exercise. However, there are natural compounds found in fruits, vegetables and spices that make your cells get rid of damaged components and mimic the anti-aging effects of intermittent fasting without the need to actually fast.

They include the following:

Berries

Berries and grapes contain stilbenes which can activate the Nrf2 signaling pathway associated with antioxidant defense and elimination of damaged cell components.  Stilbenes can also prevent cancer and prevent the progression of malignant tumors.

Red wine

Resveratrol in grapes and red wine turns on autophagy by activating AMPK and turning off mTOR.

Curcumin (turmeric)

A strong anti-inflammatory that can manage arthritis symptoms, curcumin helps your cells get rid of damaged mitochondria and can enhance the activity of lysosomes, the recycling plant of the cell where damaged components are broken down and reused.

Broccoli and Brussels sprouts

Cruciferous vegetables contain sulforaphanes. These compounds turn on the NRF2 pathway which is anti-inflammatory and prepares your cells to deal with oxidative stress.

Green leafy vegetables

Green leafy vegetables and beetroots contain nitrate (NO3–), which your mouth bacteria convert into nitrite (NO2–).  In your stomach, nitrite forms nitric oxide (NO), which can dilate blood vessels and activate autophagy through activation of AMPK.

Coffee

Polyphenols found in coffee, tea, red wine and cocoa may enhance the conversion of nitrite into NO in the stomach, which favors autophagy by turning on AMPK.

Coffee has been shown in cell culture and animal model studies to enhance autophagy in liver, muscle and even brain cells.

A study showed that caffeine promotes autophagy in the skeletal muscle of rats.

Another study found that both natural and decaffeinated coffee increased autophagy in mice 1-4 hours after coffee consumption. There was higher autophagy in the liver, heart and muscles.

Signs your cells are in cleaning mode

Unfortunately, you can’t measure cellular recycling the way you can measure blood glucose or ketones. However, ketones have been shown to induce autophagy. Therefore, if your ketone meter indicates you are in ketosis, it is also likely that your cells are getting rid of damaged cell parts at increased levels.

You can easily measure ketone levels in blood or breath throughout your fast.

Autophagy can renovate your cellular components, protect your brain by removing damaged proteins, keep diseases away by getting rid of foreign bacteria and viruses, provide your cells with energy when food is scarce, and protect you from DNA damage. Practice intermittent fasting and exercise daily! 

Track your fasts with the LIFE Fasting Tracker. Download it here.

Learn more about autophagy with our illustrated flashcard mini course!