Pace of Aging: Why How Fast You Age Matters More Than Your Biological Age

Prefer to listen? Here's a brief overview.

0:00

/97.45415

1×

You got your biological age tested. The result said 38 when your birth certificate says 44. You felt good about it. Maybe you posted it somewhere. But that number has a problem: it tells you where you are, not where you're heading. A 44-year-old with a biological age of 38 could be aging slowly, holding steady at that gap for years. Or they could be aging at 1.3 years per calendar year, meaning that comfortable 6-year advantage is shrinking fast. The static number can't tell you which scenario you're in.

Pace of aging is the metric that answers that question. Developed by researchers at Duke University and the University of Otago, the DunedinPACE algorithm measures how many years of physiological decline your body accumulates per calendar year. A pace of 1.0 means you're aging at the expected rate. Below 1.0, you're aging slower than average. Above 1.0, your body is deteriorating faster than the calendar suggests. In the Dunedin birth cohort (Belsky et al., 2022, n=1,037), pace of aging at midlife predicted mortality, disability, and cognitive decline better than any single biological age clock.

This is the difference between a speedometer and an odometer. Your biological age is the odometer. Your pace of aging is the speedometer. Both matter. But if you can only look at one, the speedometer tells you more about what happens next.

Key Takeaways

• Biological age tells you where you are; pace of aging tells you how fast you're getting there
• DunedinPACE tracks roughly 1 year of physiological change per calendar year at a pace of 1.0
• Lifestyle interventions can shift pace of aging within 12 to 24 months
• Tracking pace over time reveals whether your protocol is working or stalling

What Pace of Aging Actually Measures

Biological age clocks analyze patterns in your DNA methylation (chemical tags on your genes that change as you get older) to estimate your overall biological age. Pace of aging uses the same raw material, DNA methylation, but asks a different question. Instead of "how old does your body look right now?" it asks "how quickly is your body changing?"

Most people confuse these. Here's the distinction.

A biological age clock is like stepping on a scale. It gives you a number: 42 kilograms, 78 kilograms, whatever. Useful, but it doesn't tell you whether you're gaining weight, losing it, or holding steady. Pace of aging is like tracking your weight weekly and calculating the trend. The trend is what predicts your future weight, not any single reading.

DunedinPACE was built from 19 biomarkers tracked across the Dunedin Longitudinal Study, a cohort followed from birth to midlife in New Zealand. Those biomarkers span cardiovascular, metabolic, renal, hepatic, immune, dental, and pulmonary systems. The algorithm translates longitudinal change across these systems into a single methylation-based score that can be measured from a blood draw at any point in time (Belsky et al., 2022). In practice, this means a one-time blood test can estimate your current rate of aging without needing years of prior data.

The Problem With Static Biological Age Numbers

Biological age testing has become a consumer product. You spit in a tube or prick your finger, send it off, and get a number back. That number feels concrete. It feels actionable. But it has significant limitations that most providers don't explain.

First, biological age clocks have a measurement error of roughly 3 to 5 years (Higgins-Chen et al., 2022). If your result says 41 and your chronological age is 44, the "3-year advantage" falls within the margin of error. You might be aging well. You might be aging average. The test cannot distinguish between the two.

Second, a single biological age reading has no direction. It's a snapshot. Take two people, both chronologically 50, both testing at biological age 45. Person A has been 45 for 3 years running. Person B was 42 last year. Person A is aging slowly. Person B is aging at 3 years per calendar year. Same biological age. Radically different trajectories.

Third, biological age clocks disagree with each other. Run the same blood sample through GrimAge, PhenoAge, and Horvath's original clock and you'll get 3 different numbers. They correlate, but they measure different aspects of aging. Without context, the consumer is left wondering which number to believe.

Pace of aging sidesteps these problems by measuring rate of change rather than position. A DunedinPACE score of 0.87 means your body accumulated 0.87 years of decline per calendar year. That number is interpretable, reproducible, and actionable.

The Mistake: Optimizing a Number Instead of a Trajectory

The biggest trap in biological age testing is treating it as a score to optimize rather than a signal to interpret. People see "biological age: 38" and decide their protocol is working. They stop questioning. They stop testing. They've won.

But aging is not a leaderboard. A favorable biological age number measured once tells you about as much as a single blood pressure reading. It's data, not diagnosis. The person who tests at biological age 50 with a DunedinPACE of 0.82 is in a better position than the person who tests at biological age 42 with a DunedinPACE of 1.15. The second person is aging 15% faster than average. Their "young" biological age is a melting asset.

Most people skip this. They shouldn't.

The honest read on this is that the longevity industry has an incentive to sell you a flattering number. A test that tells you you're aging well is a test you'll recommend to friends. Pace of aging is a harder sell because it sometimes delivers uncomfortable news. But uncomfortable news you can act on beats comfortable news that means nothing.

Signals That Track Your Pace

These signals don't measure pace of aging directly, but they track the systems DunedinPACE draws from. If your hsCRP is trending upward while your fasting insulin is climbing above 10, your pace is likely accelerating even if you haven't run a formal DunedinPACE test. The table gives you proxies you can check every 3 to 6 months through standard bloodwork.

What to Do About Your Pace of Aging

1. Measure your pace, not just your age. If you're going to test your biological age, choose a platform that reports rate of change, not just a static score. A single biological age number without a pace metric is like checking your bank balance without knowing your monthly spend. Track this through Rewind, where pace metrics are built into the longitudinal dashboard.

2. Retest at 6 to 12 month intervals. Pace of aging is a trend metric. A single reading establishes your baseline. The second reading, 6 to 12 months later, tells you whether your interventions are working. Shorter intervals introduce too much noise from measurement variability.

3. Prioritize inflammation and insulin sensitivity. In the Dunedin cohort, the biomarkers most tightly correlated with accelerated pace were inflammatory markers and metabolic markers (Belsky et al., 2022). If you can move hsCRP below 1.0 and fasting insulin below 8, you're addressing the 2 largest contributors to pace acceleration. Practical steps: reduce ultra-processed food intake, maintain at least 150 minutes of moderate exercise weekly, and sleep 7 or more hours consistently.

4. Don't ignore cardiorespiratory fitness. VO2 max is the single strongest predictor of all-cause mortality (Mandsager et al., 2018). It also tracks with pace of aging. Every 1 MET increase in fitness capacity correlates with roughly a 13% reduction in mortality risk. Zone 2 training (3 to 4 sessions per week, 30 to 45 minutes each, at a conversational pace) is the highest-leverage exercise investment for pace.

5. Use your biomarker trends as a pace proxy between formal tests. You don't need a methylation test every quarter. Track hsCRP, fasting insulin, HbA1c, and lipid ratios every 3 to 6 months. If 3 or more are trending in the right direction, your pace is likely improving. If they're flat or drifting wrong, your protocol needs adjustment before your next formal pace measurement.

This is exactly the kind of longitudinal pattern Rewind was built to track. We layer methylation-based pace data alongside your quarterly bloodwork, wearable trends, and lifestyle metrics so you see whether your trajectory is improving, not just where you stand today.

Start Tracking Your Pace of Aging

Your biological age is a moment. Your pace is the story. One number tells you where you've been. The other tells you where you're going. Start tracking both with Rewind.

FAQ

What is a good DunedinPACE score?

A score of 1.0 means you're aging at the average rate. Below 0.90 means you're aging meaningfully slower than your peers. Elite scores in research cohorts cluster around 0.75 to 0.85. Above 1.10 suggests accelerated aging that warrants investigation into inflammation, metabolic health, and sleep quality.

How is pace of aging different from biological age?

Biological age estimates your body's overall physiological position relative to your chronological age. Pace of aging measures the rate at which that position is changing. You can have a young biological age but a fast pace (meaning your advantage is shrinking) or an older biological age but a slow pace (meaning you've stabilized and are holding steady).

Can you actually slow down your pace of aging?

Yes. The Dunedin study and subsequent validation cohorts show that pace of aging responds to interventions. The CALERIE trial (Belsky et al., 2023, n=220) demonstrated that a modest 12% caloric restriction over 2 years reduced DunedinPACE by 2 to 3% compared to controls. Exercise, sleep optimization, and inflammation reduction all correlate with lower pace scores in observational data.

How often should you test your pace of aging?

Every 6 to 12 months. More frequent testing adds noise without adding signal. DNA methylation patterns shift slowly, and measurement variability between draws can create false trends if you test too often. Use quarterly bloodwork (hsCRP, fasting insulin, HbA1c) as proxy indicators between formal pace tests.

Is pace of aging better than biological age testing?

They answer different questions. Biological age tells you your current position. Pace tells you your current trajectory. For making decisions about whether your health protocol is working, pace is more useful because it responds to interventions on a shorter timeline and gives you directional information, not just a snapshot.

The longevity field spent 15 years teaching people to measure their biological age. That was step one. Step two is measuring how fast that number is moving. At Rewind, we track both, because knowing where you are only matters if you know which direction you're headed.

You can't manage what you can't measure. But you also can't manage what you measure only once. Your pace of aging is the closest thing to a real-time readout of whether your body is winning or losing against time. See your trajectory with Rewind.

Rewind is a membership-based longevity platform. Individual outcomes vary.

References

Belsky, D. W., Caspi, A., Corcoran, D. L., Sugden, K., Poulton, R., Arseneault, L., ... & Moffitt, T. E. (2022). DunedinPACE, a DNA methylation biomarker of the pace of aging. eLife, 11, e73420. https://doi.org/10.7554/eLife.73420

Belsky, D. W., Huffman, K. M., Pieper, C. F., Shalev, I., Kraus, W. E., & Anderson, R. (2023). Change in the rate of biological aging in response to caloric restriction: CALERIE biobank analysis. Nature Aging, 3(2), 148-158. https://doi.org/10.1038/s43587-022-00357-y

Colilla, S., Crow, A., Petkun, W., Singer, D. E., Simon, T., & Liu, X. (2013). Estimates of current and future incidence and prevalence of atrial fibrillation in the U.S. adult population. American Journal of Cardiology, 112(8), 1142-1147. https://doi.org/10.1016/j.amjcard.2013.05.063

Higgins-Chen, A. T., Thrush, K. L., Wang, Y., Minteer, C. J., Kuo, P. L., Wang, M., ... & Levine, M. E. (2022). A computational solution for bolstering reliability of epigenetic clocks: Implications for clinical trials and longitudinal tracking. Nature Aging, 2(7), 644-661. https://doi.org/10.1038/s43587-022-00248-2

Mandsager, K., Harb, S., Cremer, P., Phelan, D., Nissen, S. E., & Jaber, W. (2018). Association of cardiorespiratory fitness with long-term mortality among adults undergoing exercise treadmill testing. JAMA Network Open, 1(6), e183605. https://doi.org/10.1001/jamanetworkopen.2018.3605