Biological age estimates how old your body actually is — derived from biomarker patterns rather than years since birth.
Mechanism — Multiple methods exist: epigenetic clocks (Horvath, GrimAge, DunedinPACE), phenotypic biomarker panels (Levine PhenoAge), telomere length, and composite functional measures (grip, gait, VO2 max). Different clocks measure different aspects of aging.
Use case — Track yearly via TruDiagnostic, MyDNAge, or InsideTracker. Look for trend, not single values. A delta of 1-3 years 'younger' than chronological is achievable with sustained lifestyle improvement.
Caveats — Commercial tests vary in reliability and reproducibility. Day-to-day variability is real. Trends over years beat single readings. Don't optimize the test at the expense of the inputs.