Autophagy is similar to intermittent fasting, but in this case, you don’t fast for weight control but disease protection. Autophagy helps the organism to regenerate and stay vital and healthy.
The basic idea is that in the absence of external sources of food, the body begins to eat itself (auto: self, phage: eat), destroying and recycling its damaged cell bits and proteins, so that new and healthy versions can be built.
It is believed to be essential for helping protect against diseases like cancer and dementia, among others.
In 2016 Japanese biologist Yoshinori Ohsumi won a Nobel Prize for his discoveries and research on the mechanisms underlying autophagy. As researchers are quick to point out, however, the field is still new and much of autophagy remains a mystery.
What is autophagy?
Recent studies have demonstrated that this kind of fasting has a greater variety of physiological and pathophysiological roles than expected, such as starvation adaptation, intracellular protein and organelle clearance, development, anti-aging, elimination of microorganisms, cell death, tumor suppression, and antigen presentation.
Additionally, in some situations, the contribution of autophagy seems to be very complicated. For example, it is very difficult to generalize the role in cancer and cell death.
This is like the question: “Is inflammation good or bad for life?” Of course, inflammation is required for the anti-bacterial response, but the inflammatory response associated with bacterial pneumonia can be life-threatening.
Therefore, it may be difficult to draw simplified connections between autophagy and higher-order functions.
Is fasting triggers autophagy?
It seems to, although most research on fasting-induced autophagy has been in animals. Fasting and calorie restriction have traditionally been associated with slower aging and longer lifespan, although their explicit role in triggering autophagy is still emerging.
As one 2018 paper put it: “the evidence overwhelmingly that autophagy is induced in a wide variety of tissues and organs in response to food deprivation.”
And the fasts have to be for 24 hours or longer?
It’s not clear. The 24-hour marker was pulled from mice studies, and mouse metabolism doesn’t necessarily correspond to human metabolism.
In an interview with the Cut, nephrologist (kidney doctor) and fasting researcher Jason Fung suggested that autophagy, in which “your body will take the oldest, junkiest proteins and burn them for energy,” happens “probably in the later stages of a long fast — somewhere around 20 to 24 hours, is my guess, and it probably maxes out somewhere around 32 hours, again is my best guess.”
Would autophagy be happening anyway, even if I never fast for that long?
Yes, although it’s hard to measure (more on that below). From what I understand, this is a process that occurs regularly within certain organisms (like people, mice, and yeast), but fasting and other forms of stress, like exercise, appear to accelerate it into a kind of cleansing overdrive.
Defects in autophagy-related genes, however, are easier to study and have been associated with the onset of certain human illnesses, like certain forms of cancer, neurodegenerative diseases (like Parkinson’s and Alzheimer’s), metabolic diseases, and autoimmune diseases.
How does autophagy benefit people?
On a basic level, autophagy is already a crucial part of cell function, in which “unnecessary or dysfunctional” cell components are disassembled, such as ones that might otherwise lead to illness.
Some studies have found that this kind of fasting help fight infectious disease, regulate inflammation, and bolster the immune system. Autophagy deficits have also been associated with depression and schizophrenia.
In people, it’s possible that increased autophagy could also contribute to increased longevity, although the connection remains hazy.
Researchers are especially interested in the way fasting-induced autophagy interacts with cancer, although its effects are complicated and unclear. Longevity researcher Valter Longo, Ph.D., recently said, on the podcast Science Vs., “Once the cancer is confused and weakened by fasting, if you then add traditional medicine, like chemotherapy, then it’s like a one-two punch.”
On the other hand, studies have also shown that autophagy can have the opposite effect, making tumors stronger and more resistant to radiation.
“Autophagy has dual roles in cancer,” per one 2011 report, “acting as both a tumor suppressor” and as a mechanism to “promote the growth of established tumors.”
Also, from a 2016 autophagy overview: “Autophagy has both positive and negative roles in cancer, and this has led to controversy over whether or how autophagy manipulation should be attempted in cancer therapy.”
There are also concerns that too much fasting-induced weight loss could be dangerous, especially among cancer patients.
So when it happens, is it just happening all over my body, everywhere?
Basically, with a notable exception: Fasting appears to induce autophagy in most organs (like the liver, muscle, and pancreas), but “not in the brain.”
Are there any benefits of autophagy that sound too good to be true but you want to include them anyway because you never know?
Well, it sort of all sounds too good to be true — this incredibly easy way to just clean up internal problems — but I especially like the vague idea that autophagy could be good for the complexion and potentially for skin diseases like psoriasis.
I also like the anecdotal stories about people who lost a lot of weight via fasting but didn’t need skin-removal surgeries afterward because their bodies “ate” the leftover skin.
As Jason Fung told me, of his fasting clinics, “We’ve never sent a single person for skin-removal surgery. We have anecdotal cases where people have lost 120, 130 pounds, and they said their skin also shrank, too. I’m like, ‘Yeah because all that excess protein needed to be burned. Not excess fat.
The body’s just not that stupid to keep around all this excess skin. Because remember, during fasting, you’re activating a pathway within your body that says, ‘Okay, we need to buckle down because we’re in a time of famine, so to speak, and we don’t need all that extra skin, so let’s burn it. And if you need it, we’ll build it again.’”
Can autophagy be harmful?
Autophagy has been described as a “double-edged sword” for its seeming ability to both “exacerbate or mitigate injury.”
Fasting, in general, can contribute to the development of gallstones, which can develop when bile stored in the gallbladder hardens into the stone-like matter.
Fasting, in general, is also not recommended for underweight people, pregnant people, children, and the very elderly.
Could fast to induce autophagy to be considered an eating disorder?
Not inherently, although excessive fasting to induce autophagy could overlap with anorexia. Many people fast for benefits beyond weight control, though, including disease prevention, muscle retention, and mental clarity.
Can you fast to induce autophagy too much, or too frequently?
Yes. There are no exact rules or recommendations (yet?), but researchers agree that extended fasting for autophagy — like going for 36, 48, or even 72 hours without food (like Jack Dorsey’s three-day water fast) — is something that healthy people should do at most 2 or 3 times a year, and only after conferring with a doctor.
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Conclusion: Autophagy simplified said, is a process where the body in the absence of food gets the order from the brain to start eating its cells. This destroys bad cells, so the organism is self-protecting from diseases.