"Biological age" has become one of the most over-sold ideas in preventive medicine. Many longevity clinics today offer three or four different tests that claim to reveal how old your body really is. Most of them are noise. A few are genuinely useful. One has been shown to respond to an intervention in a randomized controlled trial. Here's how to tell the difference.
Why chronological age is a blunt instrument
Chronological age — the number of years since you were born — is an astonishingly good predictor of disease and death. It's hard to beat. But it's also an average. Two people who are both 55 years old can be in very different places biologically. One is on track to live to 90, the other is on track to develop heart disease at 62. The chronological number doesn't distinguish between them.
Biological age is the attempt to fix this. The idea is to measure something in your body that reflects the cumulative wear-and-tear of aging — and then compare it to where you "should" be for your chronological age. If your biological age is lower, you're aging slower. If it's higher, you're aging faster.
The idea is sound. The execution is where most tests fall apart.
Why most biological age tests are noise
The first generation of biological age tests came out around 2013. They used DNA methylation patterns — chemical marks on your DNA that change as cells age — to estimate biological age. The math was clever. The results looked impressive.
The problem: nobody had shown that the tests were reproducible over time, or that they responded to interventions in a way that mattered clinically.
In 2024, a consensus review in Nature Medicine set out how biomarkers of aging should be validated before they are relied upon — a bar most commercial tests have not been shown to clear. Earlier, a 2022 analysis in Nature Aging had shown that widely used first-generation epigenetic clocks could give the same person results several years apart when the same sample was measured twice. And very few tests have any evidence that lifestyle changes can actually move the needle.
What to watch out for
If a biological age test has not been validated in an intervention study — meaning, does the score actually change when people make lifestyle changes? — it's essentially horoscope-level information. Expensive horoscope, but horoscope.
What DunedinPACE is — and why it's different
DunedinPACE was developed by researchers at Duke University and the University of Otago, based on one of the most extensively studied human cohorts in the world — the Dunedin Study, which has followed a group of New Zealanders from birth into middle age.
The "PACE" stands for Pace of Aging Calculated from the Epigenome. Instead of guessing how old you are, it measures how fast you're aging right now. A result of 1.0 means you're aging at exactly one biological year per chronological year. A result of 1.2 means you're aging 20% faster than average. A result of 0.85 means you're aging 15% slower.
It was validated in a randomized trial
This was the crucial piece of evidence that first set DunedinPACE apart from most other measures in the field.
In the CALERIE trial — a 2-year randomized controlled study of caloric restriction — healthy adults without obesity were assigned to either a 25% reduction in daily calories or their usual diet; in practice, participants achieved only about half that reduction (roughly 12%). After two years, DunedinPACE was re-measured in both groups. The caloric restriction group had a measurably — though modestly — slower pace of aging, by about 2–3%. Other epigenetic clocks, such as PhenoAge and GrimAge, did not change significantly.
A randomized trial is the strongest design for showing that a measure responds to an intervention. It means the test isn't just describing a current state — it's measuring something that can actually move in response to what people do. What it does not yet show is that slowing the score translates into less disease or a longer life; as the authors note, that would require long-term trials with clinical outcomes.
"Because of its high test-retest reliability, DunedinPACE offers a unique measurement for intervention trials and natural experiment studies." — Belsky et al., eLife 2022
Note the wording: its developers present it as a research instrument, not as an established clinical test.
What DunedinPACE can tell you — and what it can't
It's easy to get carried away with any new metric. So it is worth being clear about what DunedinPACE does and doesn't mean.
What it can tell you
- An objective, repeatable measurement of how fast you're aging biologically right now
- A baseline that can be re-measured after lifestyle changes to see if those changes are working
- A signal designed to flag faster aging before clinical signs of disease appear — although whether it does so reliably for an individual has not yet been shown
- Motivation. For many people, seeing a number they can actually move is a powerful behavioral lever
What it cannot tell you
- Whether you have any specific disease. DunedinPACE is not a diagnostic test.
- Exactly which intervention will work best for you. It's a summary metric, not a mechanistic explanation.
- Whether you will live longer or shorter than average. A faster pace of aging is associated with higher mortality, but it's not destiny.
- What to do about a high pace. That requires a proper clinical workup — cardiovascular markers, metabolic health, lifestyle factors — all of which matter more than the DunedinPACE number itself.
What actually moves the pace of aging
The trial evidence is still limited, but together with observational data it points to the unglamorous basics: caloric sufficiency (not excess), regular exercise (especially cardiovascular and strength training), adequate sleep, stress management, and not smoking. These are the same things preventive medicine has recommended for decades — but now it is possible to measure whether they're working for an individual.
Who should consider it — and how to use it
DunedinPACE is best seen as an optional extra, not a core screening test. Anyone who chooses it should receive a clear explanation alongside the result: what the number means, what it doesn't mean, and how it relates to their other clinical findings.
It does not belong in a basic preventive panel, because it is not a diagnostic test and it does not direct clinical management the way ApoB or HbA1c do. But for people who want a motivating, repeatable measurement of whether their lifestyle changes are actually working, it is currently one of the best-validated tools available. If you are considering it, discuss with your physician what you would do differently depending on the result.
The alternatives are harder to justify. NAD+ panels, telomere length tests, and most commercial "bio-age" panels do not meet a reasonable evidence threshold. The science may catch up — and is starting to: in 2025, the DO-HEALTH trial reported small effects of omega-3 supplementation on DunedinPACE and on the PhenoAge and GrimAge2 clocks. For now, DunedinPACE remains the measure with the longest track record of responding to interventions in randomized trials.
References
- Belsky DW, et al. DunedinPACE, a DNA methylation biomarker of the pace of aging. eLife. 2022;11:e73420.
- Waziry R, et al. Effect of long-term caloric restriction on DNA methylation measures of biological aging in healthy adults (CALERIE). Nat Aging. 2023;3(3):248-257.
- Moqri M, et al. Validation of biomarkers of aging. Nat Med. 2024;30(2):360-372.
- Higgins-Chen A, et al. A computational solution for bolstering reliability of epigenetic clocks: implications for clinical trials and longitudinal tracking. Nat Aging. 2022;2:644-661.
- Bischoff-Ferrari HA, et al. Individual and additive effects of vitamin D, omega-3 and exercise on DNA methylation clocks of biological aging in older adults from the DO-HEALTH trial. Nat Aging. 2025;5(3):376-385.
- Poulton R, Moffitt TE, Silva PA. The Dunedin Multidisciplinary Health and Development Study: overview of the first 40 years. Soc Psychiatry Psychiatr Epidemiol. 2015;50(5):679-693.
This article is general information and not individual medical advice. Decisions about tests and treatment belong in a conversation with your own physician.