How to read the numbers: Fact = a finding from research or biology · Term = a key term or marker worth knowing · How-to = a practical step or time frame
To activate autophagy
This time frame is based mainly on animal and indirect data – we cannot measure exactly when autophagy starts in humans. Start with a shorter overnight fast and extend it gradually; if you have diabetes, take medication or are pregnant, consult a doctor first.
Ohsumi for the discovery
Yoshinori Ohsumi won the Nobel Prize for uncovering the mechanisms of autophagy, which he studied in yeast. This is basic research – how best to apply it in humans is still being tested, so treat promises of rejuvenation critically.
The master switch
mTOR is a cellular sensor of nutrients and growth signals – when active, it promotes growth and suppresses autophagy. Your body needs both, so it makes sense to alternate periods of eating and strength training with periods of fasting rather than suppress mTOR permanently.
Autophagy (from the Greek for "self-eating") is the process by which cells break down and recycle damaged proteins, organelles and pathogens. It is cellular hygiene. When it works optimally, it removes precancerous cells, damaged mitochondria and the protein aggregates linked to Alzheimer's and Parkinson's.
mTOR (mechanistic target of rapamycin) is a kinase that blocks autophagy when nutrients are present — mainly amino acids and insulin. Without food and without insulin, mTOR "switches off" and autophagy switches on. That is why fasting works.
What autophagy is
Damaged cellular components are wrapped in a double-membrane vesicle (the autophagosome), which fuses with a lysosome. Lysosomal enzymes break the contents down into amino acids, fatty acids and nucleotides — reusable building blocks. Selective autophagy (mitophagy) specifically clears out damaged mitochondria.
How to switch autophagy on
16:8 intermittent fasting (16 hours without food) triggers baseline autophagy. Extended fasting of 24–72 hours — deep autophagy, especially in the brain. Physical exercise — training activates autophagy independently of food intake, via the AMPK pathway. A keto diet — ketosis mimics the fasted state. Spermidine (found in wheat germ, blue cheese and soybeans) activates autophagy directly. Rapamycin — a pharmacological mTOR inhibitor, promising in research, still limited in clinical use.
What blocks autophagy
Insulin — any intake of carbohydrates and protein (especially leucine) activates mTOR and blocks autophagy. Black coffee and water do not block autophagy. Alcohol impairs the liver's autophagic capacity. Chronic stress (cortisol) disrupts autophagic pathways. Lack of sleep — most autophagy in the brain takes place during sleep (the glymphatic system).
Autophagy and cancer — a nuanced view
Autophagy is a double-edged sword in cancer: in healthy cells, it suppresses malignant transformation (a tumour-suppressing role). In established tumours, it can help cancer cells survive stress (a tumour-promoting role). That is why cancer patients should discuss any autophagy-based intervention with their doctor.
