Medically reviewed content · Last updated April 2026

What Is Biological Age? TruAge, Epigenetics & How to Measure It

You have a birthday every year, and the number that comes with it is your chronological age. But researchers have known for decades that people of the same chronological age can be in wildly different states of health. Two 50-year-olds can have bodies that function like a 40-year-old and a 65-year-old respectively. The difference is their biological age.

Biological age is not an abstract concept. It is now measurable, thanks to advances in epigenetics — the study of how your genes are switched on and off by chemical modifications to your DNA. This guide explains what biological age actually is, how the science works, what your result means, and what you can do to lower it.

Biological Age vs Chronological Age

Your chronological age is the number of years since you were born. It moves in one direction at one speed. There is nothing you can do about it.

Your biological age is a measure of how well your body is functioning compared to the average person at each chronological age. It reflects the cumulative impact of your genetics, lifestyle, environment, diet, exercise, sleep, stress, and exposure to disease over your lifetime.

Here is a simple way to think about it:

• A 45-year-old who exercises regularly, sleeps well, eats a nutrient-dense diet, and manages stress may have a biological age of 38. Their cells, tissues, and organ systems function like those of an average 38-year-old.
• A 45-year-old who smokes, sleeps poorly, eats a highly processed diet, and is chronically stressed may have a biological age of 55. Their body is ageing faster than the calendar suggests.

The gap between your biological age and your chronological age is one of the most powerful health metrics available. If your biological age is lower than your chronological age, your body is ageing more slowly than average. If it is higher, you are ageing faster — and there is an opportunity to intervene.

How Epigenetic Clocks Work: DNA Methylation Explained

The science behind biological age measurement centres on epigenetics — specifically, a process called DNA methylation.

Your DNA contains roughly 28 million sites where a small chemical group (a methyl group, CH3) can attach to a cytosine base. These methyl groups act like dimmer switches — they do not change the DNA sequence itself but they influence which genes are active and which are silenced.

Here is the critical insight: the pattern of DNA methylation across your genome changes predictably as you age. Some sites gain methyl groups over time. Others lose them. By measuring the methylation status at hundreds or thousands of specific sites, algorithms can calculate your biological age with remarkable accuracy.

These algorithms are called epigenetic clocks. Different clocks use different sets of DNA sites and different mathematical models, which is why you will see multiple biological age scores reported on a single test.

How Is the Data Collected?

Epigenetic age testing requires a blood sample (not saliva — blood gives more accurate results because it contains a consistent cell population). DNA is extracted from white blood cells, treated with bisulphite (which converts unmethylated cytosines to uracil while leaving methylated cytosines unchanged), and then analysed on a methylation array — typically the Illumina EPIC array, which measures over 850,000 methylation sites in a single run.

The raw data is then processed through epigenetic clock algorithms to produce your biological age scores.

The Major Epigenetic Clocks: DunedinPACE vs Horvath vs GrimAge

Not all epigenetic clocks measure the same thing. Understanding the differences helps you interpret your results correctly.

For most people, the three most important numbers on a biological age report are:

1. Your biological age (Horvath or GrimAge) compared to your chronological age — are you older or younger than your birthday suggests?
2. Your DunedinPACE score — are you currently ageing faster or slower than average? This is the number most sensitive to lifestyle changes.
3. Your GrimAge acceleration — is your mortality-associated biological age tracking ahead of or behind your chronological age?

What Your Biological Age Result Actually Means

Getting a number is one thing. Understanding what to do with it is another.

If your biological age is lower than your chronological age

This is the result everyone hopes for. It means your body is ageing more slowly than average. A 50-year-old with a biological age of 43, for example, has cells that function like those of a typical 43-year-old. This is associated with lower risk of age-related diseases and longer healthspan.

The DunedinPACE score tells you whether you are maintaining this advantage. A DunedinPACE below 1.0 confirms that you are currently ageing slower than average — your lifestyle is working.

If your biological age matches your chronological age

This means you are ageing at approximately the average rate. There is nothing alarming about this result, but it does mean there is room for improvement. Most people who make targeted lifestyle changes can lower their DunedinPACE and, over time, reduce the gap between biological and chronological age.

If your biological age is higher than your chronological age

This is a signal that your body is experiencing accelerated ageing. It does not mean you are “old” or that the process is irreversible — it means something in your lifestyle, environment, or health history is causing your cells to age faster than the calendar. Common contributors include:

• Chronic sleep deprivation (consistently less than 7 hours)
• High levels of chronic stress
• Sedentary lifestyle with little regular exercise
• Poor diet (high in ultra-processed foods, low in vegetables and whole foods)
• Smoking (even former smoking leaves a lasting epigenetic signature)
• Chronic inflammation (visible on blood tests as elevated CRP or IL-6)
• Untreated metabolic conditions (insulin resistance, pre-diabetes)
• Excessive alcohol consumption

The important point is that biological age is modifiable. Unlike chronological age, you can change it. Studies have shown measurable reductions in biological age within 8 weeks of targeted lifestyle interventions.

Proven Interventions That Lower Biological Age

The most encouraging aspect of biological age research is that it is responsive to intervention. Here are the strategies with the strongest evidence for reducing biological age and slowing the pace of ageing:

1. Exercise

Exercise is the single most consistently supported intervention for reducing biological age. A 2023 meta-analysis published in Aging Cell found that regular exercisers had DunedinPACE scores 3–7% lower than sedentary controls. Both aerobic exercise and resistance training showed benefits.

The dose-response curve is encouraging: even moderate exercise (150 minutes of brisk walking per week) produces measurable epigenetic benefits. Higher-intensity exercise (running, cycling, swimming) and strength training show larger effects. The key is consistency — a few weeks of exercise will not shift your biological age, but 6–12 months of regular training can produce meaningful reductions.

Practical recommendation: 150–300 minutes of moderate-intensity aerobic exercise per week, plus 2–3 strength training sessions. This aligns with UK Chief Medical Officers’ guidelines and with the evidence on epigenetic ageing.

2. Sleep

Sleep is when your body performs critical repair and maintenance processes, including DNA repair, immune regulation, and metabolic housekeeping. Chronic sleep deprivation (consistently less than 7 hours) is associated with accelerated epigenetic ageing in multiple studies.

A 2024 study from the University of California found that each additional hour of sleep per night (up to 8 hours) was associated with a 0.02-point reduction in DunedinPACE. While that sounds small, it compounds over years.

Practical recommendation: Aim for 7–9 hours of sleep per night, with consistent sleep and wake times. If you suspect a sleep disorder (snoring, daytime sleepiness despite adequate time in bed), consider a sleep study — untreated sleep apnoea is a significant driver of accelerated ageing.

3. Diet

Dietary patterns strongly influence DNA methylation. The Mediterranean diet — rich in vegetables, fruits, olive oil, fish, nuts, and whole grains — has been associated with slower epigenetic ageing in cohort studies. Conversely, diets high in ultra-processed foods, added sugars, and refined carbohydrates are associated with faster ageing.

The landmark CALERIE trial (Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy) found that modest caloric restriction (25% reduction) slowed the pace of biological ageing by 2–3% over 2 years, as measured by DunedinPACE.

Practical recommendation: Focus on whole foods, adequate protein (1.6–2.2g per kg of body weight for active individuals), plenty of vegetables, and minimal ultra-processed food. You do not need to follow a named diet — consistent good eating habits matter more than any specific framework.

4. Fasting and Time-Restricted Eating

Intermittent fasting and time-restricted eating (eating within a 8–10 hour window) have shown promising effects on biological age markers in preliminary studies. The mechanisms likely involve autophagy (cellular clean-up), reduced inflammation, and improved insulin sensitivity.

A 2023 clinical trial published in Nature Aging found that a fasting-mimicking diet (5 days per month for 3 months) reduced participants’ biological age by an average of 2.5 years as measured by PhenoAge and similar clocks.

Practical recommendation: Time-restricted eating (finishing your last meal 3+ hours before bed, eating within a 10-hour window) is the most sustainable approach for most people. Periodic longer fasts or fasting-mimicking diets may offer additional benefits but should be discussed with a healthcare provider, especially if you have a medical condition or are on medication.

5. NMN and NAD+ Precursors

Nicotinamide mononucleotide (NMN) and nicotinamide riboside (NR) are precursors to NAD+ (nicotinamide adenine dinucleotide), a coenzyme essential for cellular energy production, DNA repair, and sirtuin activation. NAD+ levels decline with age, and restoring them is one of the most actively researched longevity interventions.

Human clinical trials have shown that NMN supplementation (250–1,000 mg/day) increases blood NAD+ levels within days. Early epigenetic data from the NMN REBOOT trial and other studies suggest that NMN supplementation may slow epigenetic ageing, though longer-term human data is still accumulating.

Practical recommendation: If you are interested in NMN supplementation, baseline testing with both a blood panel (to check liver function, metabolic markers, and overall health) and a TruAge biological age test provides the best foundation. Retest at 6 months to measure the impact. See our guide to testing before and after supplements for more detail.

6. Stress Management

Chronic psychological stress accelerates epigenetic ageing. A landmark study by Elissa Epel and Elizabeth Blackburn at UCSF (originally focused on telomere length, later confirmed with epigenetic clocks) showed that caregivers of chronically ill children had biological ages 9–17 years older than controls of the same chronological age.

Meditation, mindfulness-based stress reduction (MBSR), and regular relaxation practices have been shown to partially reverse stress-related epigenetic acceleration. Even modest interventions (10–20 minutes of daily meditation) showed effects in a 2022 randomised controlled trial.

7. Not Smoking and Moderate Alcohol

Smoking is one of the most powerful accelerators of epigenetic ageing. GrimAge explicitly incorporates smoking-related methylation patterns because they are so strongly predictive of mortality. Quitting smoking does not immediately erase the epigenetic signature, but it does stop further acceleration, and some methylation sites begin to normalise within 5–10 years of cessation.

Alcohol has a dose-dependent effect on epigenetic ageing. Heavy drinking (more than 14 units per week for both men and women, per UK guidelines) is associated with faster ageing. Moderate consumption shows smaller but still measurable effects in large cohort studies.

How TruAge Testing Works

TruAge is a biological age testing platform developed by TruDiagnostic, a US-based epigenetics laboratory that has processed over 100,000 tests globally. It is widely considered the gold standard for consumer epigenetic age testing and is used in clinical research by major universities and longevity clinics.

Here is how the process works with Lola Health:

1. Order your TruAge Complete test from lolahealth.com.
2. A qualified phlebotomist visits your home and draws a small venous blood sample (the same method used for all Lola blood tests).
3. Your sample is processed using the Illumina EPIC methylation array, measuring 850,000+ CpG sites across your genome.
4. Your results are analysed through multiple epigenetic clock algorithms, including Horvath, GrimAge, PhenoAge, and DunedinPACE.
5. You receive a detailed report with your biological age, pace of ageing, and actionable insights on what is driving your result.

The entire process from blood draw to results takes approximately 3–4 weeks (epigenetic analysis is more complex than standard blood testing and requires specialised laboratory processing).

Who Should Get a Biological Age Test?

Biological age testing is not a diagnostic test — it will not diagnose any disease. It is a measurement of your overall ageing trajectory. It is most useful for:

• People interested in longevity and healthspan who want to know their baseline and track the impact of lifestyle interventions over time.
• Anyone following a longevity protocol (exercise, diet, supplements like NMN) who wants objective data on whether it is working.
• People over 40 who want a deeper measure of their health beyond standard blood tests. Biological age captures ageing processes that standard blood markers miss.
• Anyone who has made significant lifestyle changes and wants to see if those changes have shifted their ageing trajectory. Testing before and 6–12 months after gives you a clear comparison.
• Biohackers and quantified-self enthusiasts who want the most comprehensive measure of ageing available.

It is not necessary for everyone. If you are primarily concerned about specific health markers (cholesterol, thyroid, iron, etc.), a standard blood test panel or advanced blood test is more immediately actionable. Biological age testing is complementary — it measures something different from standard blood work and provides a broader picture of your ageing trajectory.

Biological Age Testing vs Standard Blood Tests

A common question is whether a biological age test replaces a standard blood test. The short answer is no — they measure different things and are complementary.

The ideal approach for people serious about longevity is to combine both: a comprehensive blood panel to manage specific biomarkers and a TruAge test to monitor your overall ageing trajectory. Since both require a venous blood draw, they can often be done in the same appointment.

Common Myths About Biological Age

“Biological age is just genetics — there is nothing I can do about it”

Genetics accounts for roughly 20–30% of biological age variation. The remaining 70–80% is driven by lifestyle and environmental factors. Identical twins diverge significantly in biological age by middle age, proving that lifestyle choices matter far more than genetic inheritance for ageing.

“Online biological age calculators are just as good as epigenetic testing”

Online calculators that estimate your biological age from questionnaire answers (exercise habits, diet, sleep, etc.) are rough estimates at best. They use population-level correlations, not your actual molecular data. Epigenetic testing measures the methylation state of your DNA directly — it is the difference between guessing your weight and stepping on a scale.

“If my biological age is high, it is too late to change it”

It is never too late. The CALERIE trial showed measurable reductions in the pace of ageing in participants aged 21–50. Studies in older adults have shown that exercise interventions can slow epigenetic ageing even in people over 65. The DunedinPACE score — which measures your current rate of ageing — can change within months of a lifestyle intervention.

“You need to do everything to lower your biological age”

You do not need a perfect protocol. The evidence suggests that the biggest gains come from getting the basics right: regular exercise, adequate sleep (7–9 hours), a whole-food diet, not smoking, and moderate alcohol. Supplements, advanced fasting protocols, and other interventions offer incremental benefits on top of this foundation — they are not substitutes for it.

Frequently Asked Questions

The Bottom Line

Biological age is one of the most meaningful health metrics available today. Unlike individual blood markers that measure specific systems, biological age captures the overall trajectory of your ageing process at the molecular level. It answers a question that no other test can: how fast is my body actually ageing?

The science is robust. Epigenetic clocks have been validated in large population studies and predict mortality, disease, and functional decline better than chronological age alone. And the most encouraging finding from the research is that biological age is not fixed — it responds to the same lifestyle interventions (exercise, sleep, diet, stress management) that we already know are good for health.

If you are serious about longevity, a biological age test gives you a baseline. If you are already following a protocol, it tells you whether it is working. Either way, it turns the abstract concept of “ageing well” into a measurable, trackable number.

Related reading:

• DunedinPACE Explained: What Your Pace of Ageing Score Means
• How to Reduce Your Biological Age: Evidence-Based Strategies
• Bryan Johnson’s Biological Age Protocol: What Can You Learn?
• NMN Blood Test: How to Know If It’s Working
• Should You Test Before and After Supplements?
• Are At-Home Blood Tests Accurate? What the Evidence Says