mTOR
Anabolic growth-signaling kinase — leucine activates, fasting / rapamycin inhibits
mTOR is the cell's growth switch. Activated, it tells the cell to build proteins, divide, and store fat. Inhibited (by fasting, calorie restriction, or rapamycin), it tells the cell to recycle damaged components (autophagy) and pause growth — the longevity-promoting state. Leucine is the most potent dietary mTOR activator; this is why protein intake matters for muscle protein synthesis but excessive constant protein may be a longevity trade-off. The current consensus: maximize mTOR around training for muscle, minimize it overnight (fasting) for cellular cleanup.
The load-bearing nutrients — if these are deficient, this pathway slows down. Click any to see daily targets, food sources, and supplements that supply it.
Nutrients that contribute to this pathway but aren’t the single load-bearing inputs.