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Deep Fasting, Autophagy, and the Leap to Faith
From OMAD to long-term fasting in the final week of Lent.
Holy Week is upon us, which means preparing for Easter Sunday with a fast on Black Friday. If we fast well, our bodies will mirror and amplify our spiritual hunger and thirst on the eve of the Great Feast of the Resurrection. It is a joyful hunger—a hunger of anticipation—but a hunger nonetheless.
Having increased our fasting window each week, we now arrive at the final challenge: One Meal a Day, following the Lenten rule of St. Benedict. If you are having difficulty, you can continue the previous week’s discipline, or take a few small collations prior to the one meal. As in previous weeks, strive to be more strict on Wednesday and Friday. “Black Friday” in particular, is a mandatory fasting day in the Catholic Church, and our brothers in the Orthodox Church typically extend this fast from Thursday evening all the way to Sunday morning’s Pascha Liturgy.
Once you can comfortably fast for a whole day, the next 24 hours are much easier. Time-restricted eating, such as One Meal a Day Fasting, adapts the body to switch over to the longer-term adaptation of relying solely on one’s own internal sources for nutrition and energy.
What happens inside the body during “deep fasting” of more than 24 hours was a mystery until recent breakthroughs confirmed in scientifical terms what spiritual teachers have always reported about its cleansing effects on mind, body, and spirit. This cleansing, in turn, is a preparation for an encounter with the Divine, or a God-given mission that can only be received with the unparalleled clarity that comes from long-term fasting.
If you choose to partake in a longer fast this week, the usual warnings about consulting your physician apply. There is a second caveat, however, regarding the dangers of attempting to fast deeply without also going deeper into the spiritual essence of Lent. We shouldn’t rely on our own fickle willpower, but rather on the sustaining effects of supernatural grace. We must recall that man does not live off bread alone, “but from every word that proceeds from the mouth of the living God.”
Fasting without prayer can easily turn to pride, and we must guard against this by paying special attention to the substitutes for food that we turn to. Are we white-knuckling, and binging on black coffee or social media? Or are we using our enhanced focus and clarity wisely, setting a tone for what comes after Lent with rigorous ‘Ora et Labora’—honest labor and dedicated prayer?
Autophagy as Non-Violent Detachment
Once two brothers went to visit an old man. It was not the old man’s habit, however, to eat every day. When he saw the brothers, he welcomed them with joy, and said: “Fasting has its own reward, but if you eat for the sake of love, you satisfy two commandments, for you give up your own will and also fulfill the commandment to refresh others.” – the Sayings of the Desert Fathers
The Desert Fathers were noted both for their fasting disciplines and their long lives. The connection is unlikely a coincidence. Fasting not only cleanses your soul but also purifies and strengthens the body through a process known as autophagy, which literally means self-eating or self-digesting.
Autophagy was discovered in the 1960s by a Japanese researcher who won the Nobel Prize for his findings in 2016. In this discovery, science has finally caught up with what the Great Religions have said all along. When fasting, our cells proliferate small vesicles within themselves called Autophagosomes. These vesicles search for specific proteins and organelles marked for degradation because they are dead or no longer fulfill their purpose. They break down the oldest, most degraded proteins first and recycle them into immediately usable energy within a cell. Autophagosomes are like the Marie Kondos of the body—experts in The Art of Tidying Up.
Adalbert de Vogüé notes that this process represents a transition to a state of non-violence with respect to the outside world:
“Fasting is not only the mastery of desire on a key point, commanding the whole complex of human appetites. It is also the repose of the digestive functions, the cessation of the violence done to living things destroyed by these functions, the recollection of man within himself in a sort of detachment and self-sufficiency. From these spring pacification and spiritual refinement obtained, both when the fasting period is finished, and in the whole way of life in which fasting recurs at regular intervals.” – To Love Fasting
Accompanying autophagy is the switchover by the brain to running on ketones, produced from body fat in the liver, rather than glucose from outside sources. This likely explains the feelings of lightness and clarity De Vogüé experienced from fasting.
But the rewards don’t stop there.
Following an infection, autophagy can also eliminate intracellular bacteria and viruses. This explains why we tend to be less hungry when we get sick—the lack of appetite is the body’s wisdom telling you to give it a rest so it can focus on repairing itself.
We can speculate about why we evolved this counter-intuitive repair mechanism. During periods of extreme scarcity, humans would have needed to kick into high gear in order to acquire the resources necessary for survival. Fasting is thus a vital adaptation to a food environment where the next meal is not always readily available. We wouldn’t have lasted long as a species if we became sluggish and dysfunctional after skipping a meal or two.
All life evolves within a forcefield of stressors – from the harsh elements to other conditions of deprivation and scarcity. Most of these stressors are cyclical, or acute. We labor under the hot sun but then rest in the shade of night. We feast on the bounty of the hunt or harvest and then fast in preparation for the next.
Paradoxically, when you eliminate these cyclical stressors, the body ceases to function optimally, and in the extreme case, disease results. The body atrophies and allows the proliferation of all kinds of unbenign growth that would normally have been trimmed away during the hardship period in the stress cycle. Without some amount of stress, the body never has to “dig deep” and instead accumulates this intracellular junk, which accelerates the aging process.
We can still activate some level of autophagy in a fed state, but only at a low level. Without longer-term fasting, you are limiting the therapeutic benefits of autophagy.
It takes time to ramp up to “peak autophagy.” Dr. Jason Fung estimates that if you're eating a standard carb-heavy American diet, it will take two to three days to deplete glycogen supplies and finally enter into a truly fasted state. Once there, the rate of autophagy increases by up to five times the normal level.
From a low-carb baseline, the transition might take just 24 hours. Those on ketogenic diets can enter a fasted state in just 14 to 16 hours because of the low stores of glycogen, meaning you will trigger some amount of autophagy just through daily intermittent fasting.
Nonetheless, the occasional long-term “deep fast” will typically achieve a greater degree of autophagy than a series of shorter fasts, or even a daily routine of One Meal a Day. Again, this is because of the lopsided nature of our biology. Stress adaptations are not linear. A 36-hour fast might give you more than 3x the benefits of autophagy than an overnight fast, and a 3-day fast might be more than twice as effective at clearing out the old hunk than a 36-hour fast.
Most people can safely fast for four days or more before the body gets anywhere near the dreaded “starvation mode,” where it begins to break down vital tissue to feed itself. In the meantime, it will be burning up excess body fat, up-regulating autophagy, and generally enhancing your cellular health. Through autophagy, old defunct mitochondria are recycled into new ones, which burn energy within the cell more efficiently.
During longer fasts, the body produces an enzyme called AMPK which works as an energy sensor to detect low energy levels during fasting. AMPK stimulates the liver to burn fat and produce ketones, which helps restore the overall energy balance in cells—against the tide of insulin resistance and metabolic syndrome that is leading a majority of American adults into chronic illness.
The Science of a Miraculous Healing
The same cascade of hormone-regulated changes that has the potential to reverse obesity and diabetes also creates an environment in which it’s very hard for cancer cells to form.
Several years ago, a middle-aged woman in my parish shared a story of miraculous healing with the congregation. A few months before sharing her story, she had been diagnosed with a benign but sizable tumor that had to be removed through invasive surgery. She prayed and fasted in the days leading up to the procedure. After the surgery, the doctor reported with surprise that he had only removed a small growth compared to what had originally been detected with imaging equipment. The cancer had shrunk from the size of a fist to just a pebble.
Was this a miraculous healing or simply "autophagy"—the body's inherent ability to selectively consume the most degraded, useless, and even harmful tissues?
We don't have to choose one narrative over the other. We can give all glory to God while acknowledging that he sometimes works through biological mechanisms, aided by our faith—in this case, the willingness to try fasting. As embodied creatures, our spiritual life includes care of the body and the soul. By replacing obstacles to God's healing—such as constant worrying, or eating—with prayer and fasting, we can create the conditions for seeming miracles.
There have been many studies however that confirm this from a scientific perspective. A 2016 JAMA Oncology study on women with breast cancer found that those who fasted for more than 13 hours a day had lower rates of cancer recurrence. It’s unclear whether this comes from autophagy or lowering blood glucose levels since cancer cells use glucose as their main energy supply. Other explanations for the cancer-fighting effects of fasting center around the benefits to mitochondrial function.
Regardless of the exact mechanisms, we see life-extension and cancer-preventing benefits in all organisms, from worms to flies, suggesting that all life—not just humans—have a built-in mechanism to become more resilient and robust under semi-starvation conditions.
Autophagy from fasting is also protective against neurological diseases like Parkinson's, Alzheimer's, and other forms of dementia, and helps maintain the quality of our stem cells – the “backup cells” that help renew all our tissues, from our muscles to our bones. Stem cells are held in abundant reserve when we were young, but get depleted as we age. Most of us want to live a long life but along with that, we want to age gracefully. No one wants to get older if that means forgetting where you are, being unable to move around, and being in constant pain. Thus, we are wise to take fasting seriously – including the occasional deep fast.
In one sense, nothing could be easier than long-term fasting. Just stop eating. You don’t need an instruction manual, and the simpler you keep it, the better. You’ll find plenty of supplements and ‘life hacks’ like juice fasting to make it easier, but there is a strong argument to be made for keeping your fast to the austere version of water only, or perhaps water and black coffee or tea.
I am agnostic on whether minerals like salt and other electrolytes will help or hinder a long-term fast. They may be necessary for those doing intense exercise while fasting.
Bone broth can make the first couple of days of fasting easier when you find your energy flagging, but even the small amount of protein in it can interrupt the “deepness” of a deep fast and put autophagy on pause.
Likewise, Dave Asprey swears by Bulletproof Coffee for daily intermittent fasting, but recommends against it during longer, spiritual fasts.
I recently listened to a podcast, where my friend Case Bradford interviewed Rob Hanna about long-term fasting. The more I listen to people like Rob, the more I’m convinced that a long-term fast should aim at the highest possible degree of detachment from outside nourishment. To paraphrase Hanna, do you think Jesus, Moses, and Elijah were taking supplements with them on their 40-day wilderness retreats?
It is by periodically going without that we come to realize our true, creaturely dependence on our creator. It’s also how we realize our own greatest power as creatures—activating what Case calls the “Superstate” unlocked by long-term fasting.
So, how are we to discover that this promise is real, and not just snake oil? Once again, I return to the words of Adalbert de Vogüé, on whose intercession I’m depending to sustain me for the final week of the challenge:
To love fasting one must experience it, but to experience it, one must love it. The way to get out of this circle is easy: trust in the word of God, in the example of the saints, in the great voice of tradition, and trusting in this witness, try it.
This final week’s worksheet increases the daily fasting window to 22 hours, allowing 2 hours for renourishing with a hearty meal. A black fast, with no food or collations, is recommended on Black Friday.