How often does it make sense to remeasure your biological age?

Biological ageing clocks change slowly. In a randomised study of nearly a thousand participants, a daily multivitamin taken over two years had a small but measurable effect on two widely used clocks: the annual increase was 0.11 to 0.21 years lower than in the placebo group. That is a modest difference. The effect was greatest in people who were already biologically ageing faster at the start. Two years is therefore a logical minimum period if you want to detect the effect of a lifestyle change.

What you can track in the meantime are the behavioural patterns that do demonstrably correlate with your biological age. Sustained physical activity over twelve years was associated with a biological age that was, on average, 1.26 to 1.70 years lower than in inactive people. Large fluctuations in body weight, pulse and blood pressure over several years were associated with a 27% higher mortality risk per point on the composite score, as well as faster epigenetic ageing. Those signals are easier and more frequently trackable than an expensive clock test.

There is also a fundamental caveat to the idea of using a biological clock as a control dial. A large genetic study found no evidence that commonly used clocks such as GrimAge, PhenoAge or telomere length causally influence lifespan. This means that a lower score on such a clock does not automatically guarantee a longer life. The clock may be measuring something real, but beating the measurement is not the same as slowing ageing itself.

How worthwhile a remeasurement is therefore depends on what you want to demonstrate with it. For tracking a specific intervention such as a supplement, two years is a sensible minimum period. For monitoring your day-to-day health, indicators such as activity patterns, weight stability and blood pressure can be followed more frequently and more practically than a repeated clock measurement.