Glossary · Definition
mTOR
mTOR (mechanistic Target Of Rapamycin) is a cellular signaling pathway that regulates growth, metabolism, and protein synthesis. Activated by amino acids (especially leucine) and resistance training; inhibited by fasting and rapamycin.
Definition
mTOR (mechanistic Target Of Rapamycin) is a cellular signaling pathway that regulates growth, metabolism, and protein synthesis. Activated by amino acids (especially leucine) and resistance training; inhibited by fasting and rapamycin.
What it means
mTOR exists in two complexes (mTORC1 + mTORC2). mTORC1 is the famous one — it senses leucine + insulin + energy status, then drives protein synthesis + cell growth. The longevity community debates: chronic high mTOR activation may accelerate aging (animal studies); transient activation (post-workout, post-meal) is anabolic and beneficial. Periodic dietary restriction or fasting cycles down mTOR; eating + lifting cycles it up.
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Why it matters
Understanding mTOR is the bridge between 'eat protein to build muscle' and the longevity literature on caloric restriction. Practical takeaway: high-protein meals + resistance training to activate mTOR (build muscle); periodic fasting / time-restricted eating to give it a break (longevity hypothesis, not yet conclusive in humans).
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Frequently asked questions
Should I worry about high mTOR?
For most people training hard, no. The longevity hypothesis is strongest in animal models; human evidence is mixed. Building muscle is more important for healthspan than chasing low mTOR.
Rapamycin?
An mTOR inhibitor showing longevity-extending effects in mice. Off-label human use is happening but not well-studied. Talk to your doctor; it's not a casual choice.
Related terms
- DefinitionMuscle protein synthesisMuscle protein synthesis (MPS) is the process by which muscle tissue is built from amino acids. Triggered most strongly by resistance training + a meal containing 25-40g of high-quality protein within 2 hours.
- DefinitionMacros (macronutrients)Macros (macronutrients) are the three calorie-providing nutrient classes: protein (4 cal/g), carbohydrates (4 cal/g), fat (9 cal/g). Tracking macro split — not just total calories — improves body-composition outcomes.