Chronological age is the time since you were born. Biological age is an estimate based on selected biological features, not a definitive age for your whole body. There is no single gold-standard measurement. 1
Two people aged 50 can differ in health and function. But a result labelled “40” does not mean every organ is ten years younger. Its meaning depends on the test and what it was designed to predict. 1
Epigenetic Clocks
Epigenetic clocks analyse DNA methylation, chemical marks on DNA. Algorithms combine patterns at selected sites to estimate age-related characteristics. The clocks do not all answer the same question. 2
Horvath: The original 2013 multi-tissue clock uses 353 CpG sites. It was trained to predict chronological age across tissues, rather than directly measure fitness or remaining lifespan. 2
GrimAge: This combines methylation-based estimates of smoking exposure and plasma proteins. It predicted mortality and several disease outcomes more strongly than earlier clocks in its validation studies. 3
Those protein values are inferred from DNA methylation, not directly measured blood protein concentrations. Predicting risk also does not prove that lowering GrimAge will extend life. 3
DunedinPACE: Developed using New Zealand’s Dunedin Study, it estimates the pace of ageing. Its training data tracked changes across multiple body systems from ages 26 to 45. It reports a rate, not an age in years. 4
This makes DunedinPACE useful for research on change. However, detecting an intervention effect in a trial is different from establishing a treatment target for one person. 4
Before buying a test, ask which clock it uses, which sample type it requires, how repeatability is assessed and what a changed result would alter. Avoid comparing scores from different clocks as though they share one scale.
Biomarkers of Ageing Beyond Epigenetics
For practical health decisions, start with established risks. Blood pressure, cholesterol and blood glucose can help guide preventive care, but should not be presented as a direct reading of biological age. 5
Discuss the following categories with your clinician rather than ordering an automatic “ageing panel”:
- Metabolic health: Would HbA1c or a lipid profile help assess your risk? What additional question would fasting insulin answer?
- Inflammation: If considering hs-CRP or IL-6, why is the test needed and how would the result change care?
- Cardiovascular trends: Keep resting heart rate and heart rate variability in context. Do not convert a wearable reading into an age in years.
- Body composition and function: Consider waist trends alongside strength and everyday physical ability, rather than relying on one scan score.
BIA estimates body composition indirectly. Its skeletal-muscle and visceral-fat outputs are predictions, not direct measurements. Lean mass is also not synonymous with skeletal muscle. 6
Device-level agreement can look reasonable while an individual estimate remains uncertain. See BIA vs DEXA body composition scans for the measurement distinction. 6
Nutrition and Biological Age
In 4,500 postmenopausal women, higher Mediterranean, DASH and Healthy Eating Index scores were associated with more favourable results on several epigenetic measures, particularly DunedinPACE. 7
This was a cross-sectional study using self-reported diet. It cannot show that changing diet caused slower ageing; other behaviours and health differences may explain part of the association. 7
A practical starting point is a varied, plant-rich eating pattern: vegetables, fruit, legumes, whole grains, nuts and appropriate protein foods. Mediterranean-style eating is an option, not a promise of a younger clock score. 5
For example, add beans to a meal, choose wholegrain bread, and include a protein food such as yoghurt, tofu, eggs or fish. Focus on repeatable meals rather than a collection of “anti-ageing” ingredients.
Can Biological Age Be Reversed?
Human trials suggest some clock scores can change, but results depend on the measure used. CALERIE studied calorie restriction over two years in adults without obesity. 8
Its methylation analysis found modest slowing of DunedinPACE, without significant changes in PhenoAge or GrimAge. It did not demonstrate that participants lived longer. 8
This is not a reason to copy a calorie-restriction protocol. Discuss intentional restriction with a clinician or dietitian if you are underweight, frail, losing weight unintentionally or have an eating-disorder history.
A DO-HEALTH analysis followed 777 adults aged 70 and older for three years. Omega-3 supplementation produced small favourable changes in some clocks; additional benefits from vitamin D and exercise appeared on PhenoAge. 1
This was a post hoc analysis in generally healthy older adults. It does not establish whole-body rejuvenation or justify a universal supplement prescription. 1
Lifestyle Interventions That Matter
Aerobic activity and resistance exercise support healthy ageing. Include both, starting from your current ability. Their value should not depend on whether an epigenetic test changes. 5
Sleep, smoking cessation, stress support and social connection also belong in a healthy-ageing plan. Protect time for relationships and activities you find meaningful, rather than treating wellbeing as another score. 5
There is no need to wait for a biological-age test, and turning 50 is not a deadline. Healthy-ageing guidance remains relevant in later life. 5
Where to Start
- Choose one useful outcome: improving walking capacity, building strength or addressing a clinician-identified risk.
- Pick sustainable food and activity changes that support it.
- Agree on relevant measurements and review intervals, rather than repeatedly purchasing broad panels.
Seek clinical review for abnormal blood results, unexplained weight loss, persistent fatigue or declining function. Do not attribute new symptoms to an “older biological age”.
Our personal health dashboard guide can help organise your priorities. If you want support with nutrition and habits, explore the Longevity Programme.
For related questions, read about NAD+ and cellular ageing and inflammation in ageing.
