What adaptive age actually measures (and what it doesn't)

Short answer: adaptive age is a functional score computed from nine markers on a standard blood panel — albumin, creatinine, glucose, C-reactive protein, lymphocyte percentage, mean corpuscular volume, red cell distribution width, alkaline phosphatase, and white cell count — plus your chronological age and sex. It comes from the PhenoAge model published by Morgan Levine and colleagues in Aging in 2018 ("An epigenetic biomarker of aging for lifespan and healthspan", Aging 10(4):573–591).

Why determinism is the whole point

Most "biological age" products hand your data to a model and hand you back a number you cannot check. PhenoAge is different: it is published arithmetic. The 2018 paper's own framing was that a clinical-blood-marker-based estimator could track phenotypic aging without epigenetic assays — same inputs, same answer, every time.

Delta implements exactly that formula on your phone. No model ever computes your score. If your panel is missing one of the nine inputs, Delta refuses to score rather than guessing. Unknown units are rejected, never converted.

"DNAm PhenoAge" correlated with "all-cause mortality, cause-specific mortality ... and ... healthspan-related characteristics" — Levine et al., 2018, reporting on the epigenetic successor to the blood-marker score.

That is a claim about statistical association in a large cohort (the paper worked from the NHANES IV cohort, over 11,000 participants). It is not a claim about you. Treat the number as a trend line, not a verdict.

What it can tell you

• A baseline. One draw gives you a position. Two draws a year apart give you a direction — which is more information than most people ever get from their labs.
• A response curve. Bracket a defined 48-hour fast with three draws — before, during, after — and you learn how your body responds to a controlled physiological stress. That within-cycle response (we call it DYNAMICS) is the signal you can act on this quarter.
• A privacy-preserving track record. No account, no server holding your history. The panel photo is read and discarded; everything after that stays on the device.

What it cannot tell you

• It is not a diagnosis. Adaptive age is a wellness metric computed by a deterministic formula — it does not detect, treat, or predict disease.
• It will not hand you a dose. Any tool that tells you "take X to lower your biological age" is selling something. Delta deliberately refuses dosage guidance of any kind.
• It cannot be rushed. The multi-year gap (LEVEL) between adaptive and chronological age moves slowly. Anyone promising rapid age reversal from a number on an app is lying to you.

The safety screen comes before the number

A 48-hour fast is a real physiological stress test. Delta refuses to schedule one for anyone under 21, or for anyone with type 1 diabetes, pregnancy or breastfeeding, a history of disordered eating, advanced kidney, liver, or cardiac disease, or concurrent SGLT2 inhibitors, insulin, or sulfonylureas. A block is a block, not a warning.

Care decisions stay between you and your clinician. Delta's job is to make the measurement honest, deterministic, and private — the interpretation is a conversation, not an app screen.