From what I’ve read, the most likely candidate is a huge molecule (nearly the size of an organelle) called mTOR. Restricting calories (as well as restricting glutamate) causes this molecule to put the cell into a survive-low-food state, and so induces longevity. The obverse of this is that constant snacking probably does the opposite. There’s a good bit of research going on in this area.
Side note: mTOR means 'mammalian target of rapamycin’. The drug (named for Rapanui / Easter Island as it was first found in soil samples from there) was discovered as an immunosuppressant for transplants, then lower intermittent doses were found to have anti-aging (and age reversal in areas like hearing), then finally the molecule was isolated. I’ve been trying to pick enough cell biology and organic chemistry to understand this better.
For anyone looking at rapamycin or a rapalog, remember it’s all very experimental and could have unfortunate side effects.