#386 - Aging clocks—what they measure, how they work, and their clinical and real-world relevance

Peter Attia

Apr 6, 2026

Episode description

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In this episode, Peter takes a deep dive into the science and application of aging clocks, unpacking what they are, the differences between chronological age, biological age, and the pace of aging, and what epigenetic clocks may actually be measuring. He explores key research in the field, including a randomized controlled trial that tested simple lifestyle interventions against several commonly used aging clocks, as well as a study using brain MRI to assess the pace of aging and its relationship to dementia risk and mortality. Throughout the episode, Peter highlights the promises and pitfalls of these tools, ultimately focusing on the field's central question: whether improving an aging clock score truly translates into meaningful clinical outcomes.

We discuss:

  • Why aging clocks are being used as proxies for long-term health outcomes and the uncertainty surrounding their clinical value [2:00];

  • How aging clocks use DNA methylation to predict age and how they compare to traditional mortality prediction models [5:00];

  • The shift from aging clocks that predict chronological age to newer models that aim to measure biological age, lifespan differences, and the pace of aging [11:45];

  • The limitations of second-generation aging clocks: biological and measurement noise affecting reliability and interpretation [14:45];

  • Why aging clocks are exciting tools—compression, speed, and individual feedback [17:15];

  • The DO-HEALTH randomized trial: the study design and how different aging clocks were used to measure biological age and the pace of aging [22:00];

  • The DO-HEALTH study results: findings, takeaways, and open questions [27:45];

  • The DunedinPACNI study: how the model was developed and what it may add to the field [35:00];

  • The promise and limitations of aging clocks in measuring meaningful biological aging and predicting health outcomes [48:00];

  • Why aging clocks are not yet reliable as consumer tools and why traditional health metrics still matter most [52:00]; and

  • More.

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Mindsip insights from this episode:

Trust reliable aging clocks for consistent results

When the same interventions were tested, different aging clocks produced conflicting results, making it difficult to know which clock to trust.

Utilize Grimage clock to predict time to death

The Grimage clock is specifically trained using methylation data and other factors to predict a person's time to death, rather than just their biological age.

Utilize brain scans to estimate aging pace

One study demonstrated the ability to estimate a person's pace of aging by analyzing structural features from a single brain MRI.

Measure your aging pace for better health insights

Some advanced clocks aim to measure your current rate of aging, or how fast your system is deteriorating, rather than just assigning you a single biological age number.

Incorporate omega-3s to slightly slow aging

In a three-year study, a daily one-gram dose of omega-3s was the most consistent intervention to slightly slow aging, as measured by three of the four major epigenetic clocks.

Account for measurement noise in aging clock results

Aging clock results are subject to significant biological noise (e.g., recovering from a cold) and technical noise (e.g., sample handling), making single measurements potentially unreliable.

Incorporate biological aging clocks into life insurance models

Life insurance companies, who are experts at predicting mortality with incredible accuracy, do not currently use any of the available biological aging clocks for their models.

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