"Biological age" has become one of the most over-sold ideas in preventive medicine. Walk into most longevity clinics today and you'll be offered three or four different tests that claim to tell you how old your body really is. Most of them are noise. A few are genuinely useful. One is supported by 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 landmark review in Nature Medicine looked at the entire field. The conclusion was uncomfortable for the industry: most commercial biological age tests have not been properly validated. Many produce wildly different numbers when the same sample is tested twice. And very few 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 is the crucial piece of evidence that separates DunedinPACE from almost everything else in the field.
In the CALERIE trial — a 2-year randomized controlled study of caloric restriction — researchers assigned participants to either a 25% reduction in daily calories or a normal diet. After two years, they re-measured DunedinPACE in both groups. The caloric restriction group had a measurably slower pace of aging. The control group did not.
This is the gold standard of evidence. It means the test isn't just describing your current state — it's measuring something that can actually move in response to what you do.
"DunedinPACE is currently the most rigorously validated measure of biological aging pace available in clinical use." — Belsky et al., eLife 2022
What DunedinPACE can tell you — and what it can't
It's easy to get carried away with any new metric. So let's be 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 that may precede obvious clinical markers — changes in pace of aging can be detected before traditional biomarkers show anything
- Motivation. For many patients, 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 evidence so far 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 we've recommended for decades — but now we can measure whether they're working for you individually.
Where DunedinPACE fits in the Health Detectors program
We include DunedinPACE in our LONGEVITY module — which is strictly optional. Every patient who chooses it receives an Evidence Brief alongside their result, explaining what the number means, what it doesn't mean, and how to interpret it alongside their other clinical findings.
We do not include it in our core DETECT panel, because it is not a diagnostic test and it does not direct clinical management the way ApoB or HbA1c do. But for patients who want a motivating, repeatable measurement of whether their lifestyle changes are actually working, it is the best tool available — and it is the only biological age test we currently offer.
We deliberately exclude the others. NAD+ panels, telomere length tests, and most commercial "bio-age" panels do not meet our evidence threshold. The science may catch up. For now, DunedinPACE stands alone.
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.
- 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.