Branched-chain amino acids
Leucine-mTOR signaling
Also searched as Leucine-mTOR signaling.
The anabolic/longevity trade-off at the level of a nutrient. Leucine activates mTOR, which is exactly what muscle protein synthesis requires and exactly what the longevity literature wants inhibited. The same molecule is a muscle-building signal and a lifespan-shortening one, and no dose resolves that — only timing and context do. Elevated circulating bcaa is also an early marker of insulin resistance, which is the opposite of what the supplement claim implies.
In depth
Leucine, isoleucine and valine — and leucine is a direct mTOR signal, not merely a building block.
What drives it
Micronutrient status increases it.
Dietary protein and supplemental BCAA/EAA. Carried by the intermediary-metabolism, micronutrient and redox reviews. doi 10.3390/nu18132141 · PMC9967593
What it drives
It increases Growth restraint.
Leucine is a direct mTOR signal, not merely a building block - which is the whole basis of the sports-nutrition claim. Carried by the intermediary-metabolism, micronutrient and redox reviews (PMC9967593; doi 10.3390/nu18132141; PMC12673670; doi 10.1016/j.molmet.2023.101755). Verbatim: “Leucine is a proteogenic amino acid that also regulates many aspects of mammalian physiology, in large part by activating the mTOR complex 1 (mTORC1) protein kinase, a master growth controller”. doi 10.3390/nu18132141 · PMID 26449471 · PMC9967593
It increases Muscle.
Muscle protein synthesis requires mTOR activation. Carried by the intermediary-metabolism, micronutrient and redox reviews. doi 10.3390/nu18132141 · PMC9967593
It increases Cellular aging.
The ANABOLIC/LONGEVITY trade-off at nutrient level - the same signal that builds muscle is the one the longevity literature wants inhibited. No dose resolves it; only timing and context do. Carried by the intermediary-metabolism, micronutrient and redox reviews (PMC9967593; doi 10.3390/nu18132141; PMC12673670; doi 10.1016/j.molmet.2023.101755). Verbatim: “Here, we show that when dietary BCAAs are varied against a fixed, isocaloric macronutrient background, long-term exposure to high BCAA diets leads to hyperphagia, obesity and reduced lifespan”. doi 10.3390/nu18132141 · PMID 31656947 · PMC9967593
It reduces Insulin sensitivity.
Elevated circulating BCAA is an early marker of insulin resistance - the opposite of what the supplement claim implies. Carried by the intermediary-metabolism, micronutrient and redox reviews. doi 10.3390/nu18132141 · PMC9967593
It increases Physical performance.
Weaker evidence - mechanistically clear, trial results in protein-replete individuals inconsistent. Carried by the intermediary-metabolism, micronutrient and redox reviews. doi 10.3390/nu18132141 · PMC9967593
Blends that modulate it
Each blend page names this pathway and carries the study behind its claim.
See it on the map
Open the causal map to follow this pathway upstream and downstream, arrow by arrow, each with its study.