Does the timing of mTOR inhibition have to match the body's own pulses — feeding, exercise, sleep?

Framing gap · evidence stands at: Lifespan in mice · Atlas ID F4

The gap

Giving the drug once a week instead of daily is usually explained as a way to lower the dose and avoid side effects. But if the pathway cares about rhythm, the question is not how often you give it — it is whether the gaps in the drug line up with the moments the body actually needs the pathway on, like after a meal or after exercise. We found no study that tested this alignment for ageing or lifespan. In mice, the time of day the drug was given did change how well it worked against a tumour and how many side effects it caused.

Technical framing: Intermittent dosing is currently justified as a way to lower exposure and dodge side effects. But if the pathway reads pattern rather than level, the interesting variable is not how often the drug is given but whether the drug's troughs line up with the body's own peaks — the post-meal window, the post-exercise anabolic window, the circadian trough. We found no lifespan study that varied the phase of dosing while holding the dose and the interval constant (PubMed search, October 2026: rapamycin or everolimus combined with time-of-day, circadian or chronotherapy). Dosing time has been varied for other endpoints in mice: everolimus given when tumour mTOR activity peaked improved survival of tumour-bearing mice (OKA2013), and everolimus toxicity to the immune system and testes depended on time of day (Ozturk, Chronobiol Int 2018, PMID 29400578; Eur J Pharm Sci 2021, PMID 34242751).

What changed

The one head-to-head schedule comparison in exercising mice found that weekly and thrice-weekly rapamycin both preserved hypertrophy and grip strength, and that the schedule mattered for glucose rather than for muscle (Elliehausen, Aging Cell 2025, PMID 40704394). That is evidence that schedule does something, and a hint that the usual reason given for choosing a schedule may not be the variable that decides muscle outcomes. Intermittent dosing has also now shown lifespan extension in its own right, in female C57BL/6J mice (Arriola Apelo, J Gerontol A 2016, PMID 27091134).

What is still open

Phase, as distinct from frequency. Does the same weekly dose given before against after the feeding window, or before against after exercise, produce different lifespan, muscle and glucose outcomes? This is a cheap experiment by ageing-research standards and it has not been run.

How it could be tested

A lifespan cohort at one dose and one interval, with dosing phase as the only variable — aligned with the light-phase trough, aligned with the feeding window, aligned post-exercise. Endpoints: lifespan, grip strength and contractile force, glucose tolerance, and mTORC1 and mTORC2 substrate phosphorylation sampled at several times of day rather than once.

Why it matters

It is the practical form of F1 and it is testable now with existing drugs. If phase matters, current human trials have not controlled a variable that could change the answer.

Evidence behind this question

Probable gap. One logged PubMed search, October 2026 (rapamycin or everolimus combined with time-of-day, circadian or chronotherapy) found no lifespan study that varied the phase of dosing. PubMed only; preprints and trial registries were not searched. (checked 2026-10-15)

How it relates to the other frontier questions: The dosing-schedule form of F1.

Related evidence

• Okazaki et al. 2013 (OKA2013) — Everolimus given when tumour mTOR activity peaked improved survival of tumour-bearing mice. A tumour model, not an ageing model.
• Ozturk et al. 2018 (PMID 29400578, not in the Atlas corpus) — Everolimus toxicity to the immune system depended on time of day in mice.
• Ozturk et al. 2021 (PMID 34242751, not in the Atlas corpus) — Everolimus toxicity to the testes depended on time of day in mice.
• Elliehausen et al. 2025 (PMID 40704394, not in the Atlas corpus) — Weekly and thrice-weekly rapamycin both preserved hypertrophy and grip strength in exercising mice; schedule mattered for glucose, not muscle.
• Arriola Apelo et al. 2016 (ARR2016) — Intermittent rapamycin dosing extended lifespan in female C57BL/6J mice.

The grouping is the curator's reading of how each paper is used here. It has not been checked by a second reader.

Bears on these open questions

• Muscle-sparing, pulsed mTORC1 inhibition
• Does mTORC1-selective dosing extend lifespan, and is rapamycin's glucose intolerance a cost at all?
• Is there a low-dose mTOR schedule whose immune effects come out favourable, compartment by compartment?

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