You've probably heard about it before... Therapeutic fasting has been much talked about in recent years. Often presented as a promising natural approach to support certain pathologies, and even in the treatment of cancers! Serious research is exploring its potential in conjunction with conventional therapies.
But why and how does fasting work??
Well, the answer lies in one fascinating word... autophagy.
In 2016, Japanese researcher Yoshinori Ohsumi received the Nobel Prize in Medicine for deciphering this mechanism. Autophagy, literally "self-eating", reveals that your body has an extraordinary capacity to cleanse, repair, and regenerate itself from within.
A cellular cleansing capacity... underused!
How does it work?
Imagine our cells as small factories working tirelessly. They produce energy, make proteins, manage a thousand tasks simultaneously. And like any factory, they accumulate waste: damaged proteins, defective components, cellular debris that no longer functions correctly.
With 3 meals a day, our body is busy digesting, assimilating, building. It doesn't really have time to do a deep clean. But during fasting... everything changes! After approximately 16 to 24 hours without eating, our body switches to cleaning mode, and autophagy gradually activates.
Our cells will sort, break down, and recycle their own worn-out components.
Specifically:
Step 1: Formation of autophagosomes.
Specialized structures called autophagosomes form in the cytoplasm. These are small vesicles that will engulf:
- Damaged proteins
- Defective organelles
- Accumulated cellular debris
Step 2: Fusion and recycling.
These autophagosomes then fuse with lysosomes – true cellular "recycling factories" containing powerful digestive enzymes.
Inside this fusion, damaged elements are broken down into their basic constituents (amino acids, lipids, simple sugars) then reused by the cell.
And this process is highly selective; our cells don't randomly destroy anything! They specifically target:
- Exhausted mitochondria that no longer produce energy efficiently
- Misfolded proteins that could become toxic
- Cellular aggregates that clutter the internal space
The body in "Superman mode"
What's truly fascinating is: we are genetically programmed for this. Our ancestors survived famines, winters without food... 3 meals a day was an unthinkable luxury! The human body developed this incredible ability not to collapse when food is scarce, but on the contrary, to become more efficient, more resilient.
It activates survival mechanisms that are still there, within us. This evolutionary heritage... a real treasure hidden deep in our DNA.
Why this process is so important
Autophagy doesn't just clean, it protects. It eliminates damaged cells before they become problematic, recycles misfolded proteins that can cause diseases, and rids your body of toxic elements accumulated over time.
Some research shows that autophagy could slow down cellular aging. Others suggest a protective role against neurodegenerative diseases like Alzheimer's or Parkinson's. And that's also why fasting attracts so much interest in the field of cancer: autophagy could help eliminate abnormal cells and strengthen the resistance of healthy cells during treatments. Research is still ongoing, of course, but the avenues are serious and promising.
Effects on the brain and immunity
Brain regeneration
Autophagy triggers the production of BDNF, a protein that acts like a fertilizer for your neurons. It stimulates the creation of new connections, protects existing neurons, and even helps create new ones.
The result? Remarkable mental clarity that many people who fast report. The mind becomes clearer, sharper, as if a fog has lifted. Thoughts are more limpid, concentration increased, creativity amplified.
Immune system renewal
Autophagy also allows for a complete regeneration of the immune system. Aging immune cells are eliminated, and new, more efficient cells take their place. The entire body literally renews itself immunologically.
In parallel, chronic inflammation decreases — this silent inflammation that underlies so many modern pathologies: cardiovascular diseases, metabolic disorders, joint pain. By activating autophagy, you give your body the opportunity to lower this inflammatory level that slowly exhausts you.
Improved metabolism
When autophagy is fully activated, the body switches to ketosis and draws its energy from your fat reserves rather than glucose. This change improves our insulin sensitivity, helps regulate blood sugar, and optimizes energy metabolism.
The elimination organs – liver, kidneys – can finally focus on eliminating toxins instead of constantly managing new food intake.
In Chinese medicine, this has always been intuitively known, even if the words were different. The digestive system – the Spleen and Stomach – produces our Qi, our vital energy, but our modern lifestyle exhausts it: overly rich diet, meals eaten quickly, constant snacking, permanent stress. Fasting offers deep rest to these organs. The energy that is normally mobilized for digestion can be redirected towards repair, regeneration, cleansing. This is exactly what autophagy describes, with the words of modern science.
My personal experience with water fasting
My first time remains the most striking. The first three days were difficult: hunger in waves, some headaches, irritability. Then around day 3 or 4, everything shifted. The hunger completely disappeared, mental clarity appeared, and I felt a sudden surge of energy. This is exactly when autophagy reaches its peak activity.
I lasted a week without difficulty, and then, having gained confidence, I was able to go up to 10 days the following year in ideal conditions: mountain holidays in nature in springtime, complete isolation. The body follows without forcing when given the space to activate its natural mechanisms.
What also struck me during the refeeding was that the palate becomes hypersensitive. You taste everything in a heightened way – the sweetness of an apple, the bitterness of a salad – which reveals how much we are used to overdoses of salt, sugar, and artificial flavors.
How to fast safely?
Who should avoid it?
Let's be clear: activating autophagy through fasting is not insignificant. In Chinese medicine, we speak of a Kidney energy deficiency, which represents your deep reserves, your basic vitality. If your Kidneys are already weakened by chronic fatigue or total exhaustion, fasting risks weakening you even further.
Imagine your reserves as a bank account: fasting is investing in interior renovation work. But if your account is overdrawn, you cannot afford it.
Fasting is not recommended in cases of:
- Severe chronic fatigue or deep exhaustion
- Eating disorders (anorexia, bulimia)
- Pregnancy or breastfeeding
- Serious chronic pathologies (insulin-dependent diabetes, kidney failure, cardiovascular diseases)
- General fragility or convalescence
Essential rules
Prepare yourself gradually. Don't start overnight. Reduce your food intake in the days leading up to it: less processed foods, lighter portions, more vegetables.
Hydrate abundantly. Water fasting means you are fasting from food, not water. Drink at least 1.5 to 2 liters per day, with unsweetened herbal teas if desired.
Slow down your pace. This is not the time to run a marathon or have intense back-to-back days. Rest, walk gently, meditate, read. Fasting is also a rest for the mind.
Take care with refeeding. This is CRUCIAL, and it is often where mistakes are made. Your digestive system is completely at rest; it needs to be gently reawakened: diluted vegetable juices, broths, then gradually ripe fruits and cooked vegetables before returning to a normal diet. The longer the fast, the more gradual the refeeding must be.
Seek support. For a first fast or a fast of several days, support can be truly invaluable. Do not hesitate to discuss it with a trained practitioner.
What this tells us about our body
Autophagy reveals something profound: our body possesses an intelligence far beyond what we imagine. It knows how to repair, cleanse, and optimize itself if we give it the opportunity.
This mechanism has always existed within us, engraved in our DNA by millennia of evolution. Fasting is just one way to activate it, to create that space where your body can finally do what it knows best: take care of itself.
Understanding this allows us to return to the same fundamental questions, necessary for all healing:"What is my body trying to express? What does it need, and am I ready to listen?"
