Biologic age tests promise a single number that captures "how old your body really is." The science behind them is real - DNA methylation patterns track aging more accurately than the calendar. The clinic interpretations are often oversold. Here's what these tests actually measure, what they're useful for, and the right way to retest.
What's being measured
DNA methylation clocks (Horvath, Hannum, GrimAge, PhenoAge, DunedinPACE) read methyl groups at specific cytosine sites across the genome. These methylation patterns shift predictably with age and exposure - smoking, sleep loss, infection, chronic inflammation all leave fingerprints.
Different clocks answer different questions. Horvath and Hannum estimate chronological age from methylation - useful for forensic-style age estimation. PhenoAge and GrimAge estimate biological age (predicted mortality risk). DunedinPACE estimates pace of aging (how fast you're aging right now, in years per year).
DunedinPACE is arguably the most actionable consumer-available output: a value of 1.00 means you're aging at the population average. 0.85 means you're aging slower than chronological time; 1.20 means faster.
What they predict (and don't)
GrimAge and PhenoAge correlate with all-cause mortality, cardiovascular events, and cancer in large cohorts (Health and Retirement Study, Framingham). The predictive signal is real but inexact - confidence intervals are wide for individuals.
These tests do not diagnose disease, identify specific organ aging, or replace standard biomarker work (ApoB, HbA1c, fasting insulin, hs-CRP). They are population-level age estimates applied to one body.
Test-retest reliability matters. Some commercial methylation tests show ±2-3 year variability between identical samples. Run the same lab twice for any baseline comparison; cross-lab comparisons are unreliable.
How to use the result
Baseline reading: useful as a single data point - especially if your standard markers (ApoB, HbA1c, etc.) are already optimized and you want to track aging-rate signals at a higher level.
Trajectory tracking: most useful when retested every 12-18 months from the same lab, on the same clock (DunedinPACE preferred for pace tracking). Faster than annual makes the signal-to-noise ratio bad.
Behavior linkage: a slowing pace correlates with consistent sleep, training, low inflammatory load, and metabolic optimization. There's no shortcut supplement that reliably moves these clocks - the things that work are the same things that work for ApoB and HOMA-IR.
What we run, what we skip
We offer the Biologic Age panel for members who want the methylation-clock data alongside the metabolic and hormone panels. We do not require it - the standard Advanced panel covers more clinically actionable ground.
We skip telomere length tests at consumer clinics. Telomere assays have higher technical variability than methylation clocks and the predictive validity for individuals is weaker. Useful in research, less so in primary prevention.
We skip aging-clock-driven supplement recommendations. "Take this stack to slow your aging clock" is not how the evidence reads. Sleep, training, and ApoB optimization are the validated levers.
What to do now
If standard markers (ApoB, HbA1c, fasting insulin, hs-CRP, hormones) are already optimized and you want one more longitudinal signal, the Biologic Age panel is reasonable. We use DunedinPACE-style outputs to track over 12-18 months.
If the standard markers aren't dialed yet, run the Advanced panel first. ApoB at 70 vs 100 will move your real risk picture more than any methylation reading.