Intro
Chronological age is the number of years you’ve lived.
Biological age is an estimate of how your body is functioning relative to typical aging patterns.
This matters because two people with the same chronological age can have very different risks for disease, disability, and loss of independence.
Key Points
- Biological age is an estimate, not a diagnosis.
- Different tests measure different things (and may disagree).
- Many tests are best used to track direction over time, not a single number.
- Improving fitness and metabolic health is a practical way to improve “functional age.”
What Biological Age Tests Measure
Common approaches include:
- Epigenetic clocks (DNA methylation patterns)
- Blood biomarker panels (metabolic and inflammation markers)
- Fitness / function metrics (VO₂ max, strength, gait speed)
- Composite scores (mix of labs + function)
Limits and Pitfalls
- Results can vary with sleep, illness, stress, training load, or weight change.
- A single test result is noisy; trends across time are more meaningful.
- Commercial claims may outpace evidence.
Practical Interpretation
- Use biological age tools as feedback for lifestyle changes, not destiny.
- Prioritize:
- strength + aerobic fitness
- metabolic health (waist, blood pressure, glucose)
- sleep and recovery
FAQ
Q: What’s the difference between biological and functional age?
A: Functional age usually refers to performance (strength, endurance, mobility). Biological age may refer to biomarker-based estimates.
Further Reading
- PubMed: “epigenetic clock” review literature
- National Institute on Aging: aging biomarkers overview
Related Guides
- [/guides/healthspan-vs-lifespan]
- [/guides/intrinsic-vs-extrinsic-mortality]
- [/guides/what-determines-human-lifespan]