Biological age
Also called: epigenetic age
Clinical reviewer: Jacob Moore, MD · Last checked September 22, 2026
What is biological age?
Biological age is an estimate of how old the body appears based on molecular or physiological markers, rather than years since birth. Researchers most often calculate it from DNA methylation patterns, called epigenetic clocks; a widely used version, developed from 8,000 samples across 51 tissue types, uses 353 methylation sites on the genome.
What is an epigenetic clock?
In 2013, a widely cited study built a DNA methylation age predictor from 8,000 samples spanning 51 healthy tissue and cell types, identifying 353 CpG sites that together form an aging clock [1]. A later clock called GrimAge, published in 2019, combines seven DNA methylation surrogates with a smoking-history estimate into one score, and its developers report it predicts time to death, coronary heart disease and cancer better than earlier clocks [2]. A 2024 review found biological clocks fall into two families, phenotypic clocks built from standard blood tests and epigenetic clocks built from methylation data, and compared the predictive performance of 33 of them [3].
Can lifestyle changes lower biological age?
The evidence is preliminary. A small pilot trial randomized 43 healthy men aged 50 to 72 to an 8-week diet, sleep and exercise program or a control group, and found the program lowered a DNA methylation age score by 3.23 years relative to controls (p=0.018); the study's own authors are named in a related patent application and call for larger, longer-duration trials to confirm the finding [4].
Related terms
Sources
- Horvath S. DNA methylation age of human tissues and cell types. Genome Biol, 2013.
- Lu AT et al. DNA methylation GrimAge strongly predicts lifespan and healthspan. Aging, 2019.
- Warner B et al. A systematic review of phenotypic and epigenetic clocks used for aging and mortality quantification in humans. Aging, 2024.
- Fitzgerald KN et al. Potential reversal of epigenetic age using a diet and lifestyle intervention, a pilot randomized clinical trial. Aging, 2021.
This entry is for education and is not medical advice. Talk with a licensed clinician about your own situation before starting, stopping, or changing any treatment.
