I recall him saying he wouldn't recommend people younger than about 40 take mTOR inhibitors too, worth noting for young longevity enthusiasts. As I understand mTOR activation/inhibition is a tradeoff between promoting and inhibiting "growth" and the latter is counterproductive for young people. IIRC high meat/protein diets also activate mTOR, which might partially explain why primarily plant-based diets are associated with longer lifespans. Fasting also suppresses mTOR, so mTOR inhibitors are sometimes promoted as an easier way to achieve (some of) the same benefits more easily. On the other hand fasting elevates cortisol which inhibits testosterone. I don't know if mTOR inhibitors like rapamycin have the same effect, but it's also a health concern.