Biological Age: What an Estimate Can and Cannot Tell You

An estimate, not your body’s true age

Chronological age is the time since your birth. It remains useful in medicine, but people of the same age can differ in their physical capacities and health.

Biological age is a family of estimates derived from biological data. There is no single measurement that reveals the true age of the whole body. The result depends on the method, the sample and the population used to develop the model.

Different clocks answer different questions

Some epigenetic clocks use DNA methylation patterns to estimate an age. Horvath’s 2013 work is an example [1]. Other models were developed for different objectives, including associations with health outcomes. Their results are not interchangeable.

An age difference and a pace of aging are also different concepts. A model estimating 45 years in a person aged 40 produces a difference of five years. That does not mean the person ages five times faster or has five fewer years to live. DunedinPACE was developed to estimate a pace from longitudinal changes across several biological systems [2].

Associations observed in research populations do not establish an individual’s diagnosis or future lifespan. A facial appearance estimate is not equivalent to a molecular clock either.

How to interpret a change

Before comparing two results, ask whether the same method and sampling conditions were used. Measurement variability, temporary changes in health or habits, and updates to a model can affect the comparison.

A lower estimate alone does not prove rejuvenation, a benefit from a supplement, or added years of life. Repeated observations can provide context; they do not, by themselves, establish what caused a change.

For everyday decisions, activity, sleep, nutrition and how you feel remain useful things to discuss and follow. They do not need to be converted into an age to matter.

How this relates to TwinMe

The TwinMe Healthspan / Longevity program describes a resilience score across five dimensions: vascular resilience, immune resilience, bone reserve and supporting tissues, hormonal adaptation, and liver metabolic processing.

This score is neither an age, a diagnosis, nor a prediction of longevity. It should not be presented as an epigenetic clock or as a promise to reverse aging. The program details explain the information included in that experience.

Sources

Horvath S. DNA methylation age of human tissues and cell types. Genome Biology, 2013. doi:10.1186/gb-2013-14-10-r115.
Belsky DW et al. DunedinPACE, a DNA methylation biomarker of the pace of aging. eLife, 2022. doi:10.7554/eLife.73420.