mTOR

💡 Did you know? mTOR is your body's growth switch: on, you build muscle; off, cells clean house through autophagy. You can't max both at once — you cycle them.

In one line: The master switch that tells cells "there's plenty of food — grow."

Picture this: mTOR is a foreman who watches the supply yard. When protein and energy are plentiful, the foreman shouts "build!" and the cell grows and adds muscle. When supplies run low, the foreman goes quiet and the crew switches to cleaning and repairing instead.

What it really is: mTOR is the central control point for growth in every cell. Turn it on to build muscle; turn it off to trigger cleanup and, in animals, longer life. This is the tension at the heart of fitness-versus-longevity: you cannot have the "grow" switch fully on and fully off at once.

Step by step:

You eat protein (especially the amino acid leucine) and your insulin rises.
That signals abundance, and mTOR switches on.
mTOR ramps up muscle protein synthesis — the cell builds.
At the same time it dials down autophagy, the cell's recycling and self-cleaning.

Why it matters for you: If your goal is muscle, you want to spike mTOR after training — protein and leucine do exactly that. If your goal is longevity, you periodically want mTOR low (via fasting or the drug rapamycin) so cells clean house.

Turn it up: protein, leucine, whey, insulin, resistance training. Turn it down: rapamycin, fasting, going low on protein. Its energy-sensing opposite is the AMPK pathway.

Don't be fooled: more mTOR isn't always better. Chronically high growth signalling is linked to faster ageing — the goal is to spike it around training, not keep it pinned on all day.