What is autophagy?
Autophagy, literally "self-eating", is the process by which your cells break down and recycle their own damaged components: misfolded proteins, worn-out mitochondria, toxic aggregates. Discovered in the 1960s, its molecular mechanisms earned Yoshinori Ohsumi the Nobel Prize in Medicine in 2016.
Without autophagy, waste accumulates in the and the cell ages prematurely. With active autophagy, the terrain stays functional for longer. It is one of the identified biological pillars of healthy longevity.
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Le cycle de l'autophagie
The three main pathways
- Macroautophagy — the cell wraps its waste in a double membrane () and then fuses it with a that digests it.
- Microautophagy — the lysosome directly engulfs small pieces of cytoplasm.
- Chaperone-mediated autophagy — proteins carrying a specific tag are imported one by one into the lysosome.
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Trois voies d'autophagie
, the targeted recycling of defective mitochondria, is a subtype particularly studied for its role in cellular ageing and neurodegenerative diseases.
AMPK and mTOR: the two switches
Autophagy is governed by two energy sensors that act as mirror images of each other:
- (mechanistic Target Of Rapamycin) activates when nutrients are abundant (amino acids, glucose, insulin) and inhibits autophagy to push growth.
- (AMP-activated Protein Kinase) activates when energy is scarce (fasting, exercise, high AMP/ATP ratio) and switches on autophagy to save and recycle.
Interactive diagram
The cellular balance
Click Restriction or Abundance to see what each state triggers inside the cell. The two systems cannot dominate at the same time.
A lifestyle that never engages AMPK — constant caloric intake, sedentary habits, snacking — lets mTOR dominate permanently. Autophagy goes dormant, waste accumulates.
Intermittent fasting: what the science says
Fasting windows lower insulin and glucose, which reduces mTOR signalling and releases the brake on autophagy. The most studied protocols:
- 16:8 — 16 h fasting, 8 h eating window. The most accessible format, with measurable metabolic effects (fasting glucose, insulin sensitivity).
- OMAD (one meal a day) — a single meal per day. More demanding, best kept for tolerant terrains.
- Prolonged fasting (48–72 h) — used in the clinic under supervision to target regeneration of the immune system (work of Valter Longo).
- FMD (Fasting Mimicking Diet) — 5 days of very reduced intake that mimic fasting without all its drawbacks.
Calorie restriction and longevity
In animals, a 20 to 40 % calorie restriction without malnutrition extends lifespan reproducibly. In humans, the CALERIE study shows clear cardiometabolic benefits over two years, with no longevity data available at this stage. The central mechanism: less mTOR signalling, more AMPK, more autophagy, less chronic inflammation.
Precautions and limits
Fasting is not for everyone. To be avoided or supervised in cases of: pregnancy and breastfeeding, history of eating disorders, insulin-treated diabetes, undernutrition, low muscle mass (sarcopenia), adrenal disease. Muscle building relies on mTOR: during a muscle-gaining phase, long fasts can be counterproductive.
Individual relevance depends on the terrain, age, goal and overall stress level. Autophagy is a lever, not an end in itself.
This article is educational and does not constitute medical advice. A plan for prolonged fasting or calorie restriction should be discussed with a healthcare professional familiar with your terrain.