mTOR. Growth or Repair.

Your body cannot fully build and fully repair at the same time. mTOR is the switch that decides which mode it is in.

What It Does
  • When mTOR is active — the body builds. Protein synthesis increases, cells grow, muscle is repaired and made.
  • When mTOR is suppressed — the body repairs. Autophagy increases, damaged proteins and organelles are broken down and recycled, inflammation reduces.
  • The two states are in tension. You cannot maximise both simultaneously.
What Keeps It High
  • High protein intake — specifically leucine — activates mTOR through amino acid sensing. A standard meal of meat exceeds the activation threshold at normal serving sizes.
  • High carbohydrate intake activates mTOR through a separate pathway — the insulin response. The two pathways are independent.
  • A high-protein, high-carb diet activates both simultaneously. Modern diets rarely give the body a suppression window.
  • Exercise activates mTOR locally in muscle — this is intentional and useful. The body localises the signal to where it is needed.
Why Chronic Activation Is a Problem
  • Persistent mTOR activation is associated with impaired autophagy, cellular senescence, mitochondrial dysfunction and chronic inflammation — recognised hallmarks of ageing.
  • The body needs regular periods of low mTOR to run its repair and cleanup processes.
The Longevity Connection
  • In animal models, mTOR suppression extended lifespan by 10–30% even when started late in life.
  • Human lifespan data does not yet exist — the animal evidence is promising but unproven in humans.
  • Periodic suppression, not chronic suppression, is likely the right model. The body evolved to cycle between fed and fasted states — not to sit permanently in either.
The Practical Levers
  • Fasting — the most direct way to suppress mTOR. Both amino acid availability and insulin drop, quieting the signal through both pathways.
  • Lower carbohydrate intake reduces the insulin pathway. Lower protein intake reduces the leucine pathway. Both lower the cumulative daily signal without fasting.

The pattern the body was designed for: periods of activation — eating, training — followed by periods of suppression. Not permanent elevation. Not permanent suppression. Cycling.

PS. The goal is not to suppress mTOR. It is to stop keeping it permanently on.