Written by Dr Elaine O’Connor-Haq, MB BCh BAO, MPharm, L7Dip(Aes)
Medical Aesthetics Doctor and founder of Bespoke Medical Aesthetics, Colchester
Most of us grew up thinking about age in birthdays: 30, 40, 50, 60, but anyone who works with people’s health and skin sees very quickly that years lived and how your body is actually ageing are not the same thing. This is what I often see in clinic.
The gap between the number on your passport and what’s happening inside your cells is the difference between chronological age and biological age. Your biological age is shaped by inflammation, lifestyle, hormones, sleep, stress, nutrition, and environment and it can move faster or slower than your chronological age.
In this article, I’ll explain:
- What biological age really is
- The hidden factors that accelerate (or slow) ageing
- How biological age is measured
- Where GlycanAge fits into the picture
- Why this matters for long-term health, skin and wellbeing
So whether your goal is healthy skin, more energy, better ageing, or all three, this is your overview of what’s really driving “how old” your body is.
What Do We Mean by “Biological Age”?
Chronological age is simply the number of years since you were born. Biological age describes how the body is ageing internally at a cellular, metabolic and immune level. Although we cannot see these processes directly, biological age can be estimated using biomarkers that reflect the pace and quality of ageing beneath the surface.
“One of the most important distinctions is that biological age can move faster or slower than chronological time.”
Biological age is influenced by:
- Chronic inflammation and immune activity
- Metabolic health and blood sugar control
- Hormonal balance
- Sleep quality and circadian rhythm
- Psychological stress
- Nutrition, movement and lifestyle habits
- Environmental exposures (such as smoking or pollution)
These systems interact closely with one another. For example, chronic stress can elevate cortisol, which affects insulin sensitivity, immune function and sleep, leading to metabolic strain and increased inflammation – all of which can accelerate biological ageing.
One of the most important distinctions is that biological age can move faster or slower than chronological time. Large cohort studies show that individuals with biomarkers indicating accelerated biological ageing have higher risks of frailty, cognitive decline, metabolic disease and earlier mortality, while those with a younger biological age tend to maintain better functional health for longer (Belsky et al, 2022).
This does not mean biological age predicts individual futures; rather, it offers a physiological snapshot of how the body is coping with life right now. For many people, understanding biological age can be a powerful catalyst to improve sleep, nutrition, stress regulation, movement patterns and metabolic health, choices that support long-term wellbeing and healthspan.
What Drives Faster (or Slower) Biological Ageing?
Ageing is not caused by one single process. Instead, it reflects the cumulative effect of multiple biological systems interacting over time.
Some of the most important drivers include:
1. Chronic Inflammation
Low-grade, persistent inflammation plays a central role in modern ageing science, often called “inflammageing”. Over time, it affects immune function, blood vessels, metabolism and connective tissue, including skin.
2. Metabolic Health & Glycation
Insulin resistance, blood sugar instability and highly processed diets accelerate biological ageing through pathways linked to glycation and oxidative stress. They contribute to the formation of advanced glycation end-products (AGEs). These cross-link collagen and other proteins, making tissues stiffer and less resilient. In skin, this can show as:
- Loss of elasticity
- Yellowing or sallow tone
- Coarser texture
At a systemic level, higher AGEs and poor glycaemic control are linked to cardiovascular disease, kidney disease and faster biological ageing.
3. Oxidative Stress & Mitochondrial Function
Oxidative stress arises when reactive oxygen species (ROS) outweigh antioxidant defences. Over time, ROS can damage lipids, DNA and proteins, affecting everything from mitochondrial function to collagen and elastin integrity.
Lifestyle factors that increase oxidative stress include:
- Smoking
- High alcohol intake
- Pollution
- Chronic psychological stress
- Poor diet low in antioxidants
Antioxidant-rich diets (colourful plants, polyphenols, omega-3 fats) are associated with more favourable biological ageing markers in several cohorts (Maksimović et al, 2025).
4. Lifestyle: Sleep, Stress, Movement
Sleep: Deep (slow-wave) sleep is a key window for DNA repair, hormonal balance and collagen synthesis. Chronic sleep restriction is associated with higher inflammatory markers, impaired glucose tolerance, and adverse epigenetic ageing signatures.
Stress: Long-term elevated cortisol alters immune function, increases visceral fat (deep fat surrounding vital organs), disrupts sleep and can accelerate epigenetic and inflammatory ageing pathways.
Physical activity: Regular movement, particularly a mix of aerobic and resistance training, is consistently linked to lower biological age and slower epigenetic ageing in large datasets.
Can Biological Age Change?
Human research suggests that biological age is modifiable, although changes are typically modest rather than dramatic.
Studies examining lifestyle interventions, including improved nutrition, physical activity, sleep optimisation and stress management, show that biological ageing markers can shift in a more favourable direction over weeks to months.
This does not mean ageing can be “reversed” in a simplistic way. Rather, it suggests that:
- Measuring biological age may help guide more informed lifestyle choices
- Ageing is dynamic, not fixed
- Daily habits influence how quickly ageing processes progress
How Is Biological Age Measured Today?
There is no single perfect test for biological age. Different tools look at different aspects of how the body ages, which is why results can vary depending on what is being measured. Broadly, current approaches include:
1. Epigenetic Clocks (DNA Methylation)
These tests analyse patterns on DNA that change predictably with age. Well-known research-based examples include the Horvath clock and newer models designed to estimate health risk or pace of ageing. They are useful for population-level insights, but individual interpretation is still evolving.
2. Blood-based composite markers
Some approaches combine routine blood markers linked to inflammation, metabolism and organ function. These can give a broad health snapshot, but may be influenced by short-term illness or fluctuations.
3. Immune-based markers
These focus on how the immune system behaves over time, particularly patterns linked to chronic inflammation. GlycanAge is an example of this approach, examining immune-related changes that tend to shift with ageing and lifestyle.
Where Does GlycanAge Fit In?
GlycanAge is a blood test that estimates biological age by examining patterns linked to immune system ageing and inflammation.
Rather than looking at DNA, it focuses on how the immune system behaves, specifically whether it appears more balanced and “youthful” or more chronically inflamed than expected for a given age (Gudelj et al, 2018) .
This makes GlycanAge particularly relevant for:
- Understanding inflammatory ageing
- Exploring immune health as part of longevity planning
- Providing a stable, reproducible biological age signal
Like all biological age tests, GlycanAge does not diagnose disease or predict outcomes. It offers directional information that can be used to support informed discussions about health, lifestyle and ageing (Hoshi et al, 2024).
Why Biological Age Matters for Skin and Appearance
Although biological age affects the entire body, the skin is often where its effects are most visible. Chronic inflammation, oxidative stress and metabolic dysfunction can accelerate:
- Collagen breakdown
- Loss of elasticity and firmness
- Changes in skin texture and tone
- Impaired barrier repair
This is why two people in their 40s can have very different skin quality and ageing patterns, not because of birthdays alone, but because their underlying biology and lifestyle exposures differ.
Understanding biological age allows us to place skin ageing within a whole-body context, rather than treating it as a purely cosmetic issue.
How We Use Biological Age Testing in Practice
At Bespoke Medical Aesthetics, we use biological age testing, including GlycanAge, as part of a broader, longevity-informed approach to skin and health. The result is not a verdict or diagnosis. It provides clinically meaningful context that helps guide personalised discussions around lifestyle, skin health and long-term ageing.
Biological age testing can help us:
- Explore how inflammation and lifestyle may be influencing ageing
- Identify areas where targeted changes may be beneficial
- Personalise skincare, lifestyle and treatment strategies
- Track changes over time, if testing is repeated
We do not use biological age tests to make guarantees or diagnoses. They are one piece of a much larger picture, but a scientifically grounded and increasingly useful one.
Bringing It All Together
Chronological age tells us how long we’ve lived. Biological age offers insight into how we’re ageing, and how lifestyle, inflammation and recovery may be shaping that process over time.
Tools such as GlycanAge are not designed to create fear or pressure. Their value lies in helping make an abstract concept, ageing, more tangible, measurable and open to informed influence through everyday choices.
If you’re interested in:
- Understanding your biological age
- Exploring how inflammation and lifestyle may be affecting it
- Taking a more evidence-based, whole-body approach to skin health and ageing
You’re welcome to book a consultation, either in-clinic or remotely.
FAQs About Biological Age
Q1: Is biological age the same as life expectancy?
No. Biological age reflects how your body is ageing at the moment. It does not predict lifespan or guarantee future outcomes.
Q2: Can biological age be reversed?
Research suggests biological ageing markers can shift in a more favourable direction with lifestyle changes, but this is better thought of as influencing the rate of ageing rather than reversing it.
Q3: Is GlycanAge a diagnostic test?
No. GlycanAge does not diagnose disease or replace medical assessment. It provides contextual information about immune ageing and inflammation.
Q4: Who is biological age testing most useful for?
It may be helpful for people interested in prevention, longevity, skin health or tracking the impact of lifestyle changes over time.
Q5: Should everyone test their biological age?
Not necessarily. Biological age testing is optional and most useful when results are interpreted thoughtfully within a clinical context.
Q6: How often should biological age be tested?
If repeated, testing is usually spaced months rather than weeks apart, as meaningful biological changes take time.
References
Belsky, D.W., Caspi, A., Corcoran, D.L., Sugden, K., Poulton, R., Arseneault, L., Baccarelli, A., Chamarti, K., Gao, X., Hannon, E., Harrington, H.L., Houts, R., Kothari, M., Kwon, D., Mill, J., Schwartz, J., Vokonas, P., Wang, C., Williams, B.S. and Moffitt, T.E. (2022) ‘DunedinPACE, a DNA methylation biomarker of the pace of aging’, eLife, 11, e73420. doi: 10.7554/eLife.73420.
Gudelj, I., Lauc, G. and Pezer, M. (2018) ‘Immunoglobulin G glycosylation in aging and diseases’, Cellular Immunology, 333, pp. 65–79. doi: 10.1016/j.cellimm.2018.07.002.
Hoshi, R.A., Plavša, B., Liu, Y., Trbojević-Akmačić, I., Glynn, R.J., Ridker, P.M., Cummings, R.D., Gudelj, I., Lauc, G., Demler, O.V. and Mora, S. (2024) ‘N-glycosylation profiles of immunoglobulin G and future cardiovascular events’,
Circulation Research, 134(5). doi: 10.1161/CIRCRESAHA.123.323623.
Maksimović, T., Gădău, C., Antal, G., Čoban, M., Eșanu, O., Atyim, E., Mioc, A., and Codruța Șoica (2025) ‘Polyphenol-based therapeutic strategies for mitochondrial dysfunction in aging’, Biomolecules, 15(8), pp 1116:. doi: 10.3390/biom15081116