Is Your Birth Certificate Lying? How To Tell If Your Biological Age Differs From Chronological Age

Reviewed by Jeremie Walker, MD, MBA · June 20, 2023
biological age

Suppose you’re about to turn the big 5-0 or 6-0. Your friends throw you a party, and to make you feel better, they tell you, “50 is the new 40” or “60 is the new 50.” But what if your biological age is actually greater than the number of candles on your birthday cake? Your chronological age (the number of years you have been alive) can drastically differ from your biological age. So how can you tell how old you are on the inside?

This article will answer:

  • What is biological age?
  • How is biological age calculated?
  • What’s the difference between biological age vs. chronological age?
  • What mechanisms influence biological age?
  • What lifestyle factors affect biological age?
  • How can you reverse biological age?

Notwithstanding the COVID-19 pandemic and the opioid crisis, both of which have caused the average lifespan in the U.S. to decline in recent years, because of a sharp decline in tobacco smoking, greater awareness of the importance of nutrition and exercise, and other factors, people generally live longer than in decades past. For example, in 2021, nearly 90,000 U.S. residents were at least 100 years old, nearly twice as many centenarians as two decades ago. 

While lifespans have increased, many people are aging faster than their chronological age. Take two 50-year-olds. One may look a decade younger and have a biological age that reflects this youthful appearance. In contrast, the other has a biological age closer to 60. 

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What Is Biological Age? 

Biological age is a measure of how quickly your body is aging. It is influenced by a combination of factors, including your genetics, lifestyle choices, and demographics.

Biological age is a method that uses biophysiological measures to better assess the risk of negative outcomes associated with aging, according to a study in Current Oncology Reports.

In other words, you can’t tell how well a car runs unless you get under the hood and examine the engine. In the same way, biological age measures overall internal bodily function. So it reflects better than chronological age whether an individual will develop a chronic illness and how close they are to blowing out their last birthday candle.

“Biological age aims to give a more ordered relation between an individual’s current health state and their proximity to death. This, in turn, can enable a novel approach to individualizing care and potentially yield ways in which aging might be modified,” writes the co-authors of the Current Oncology Reports study. 

But how can you tell how many years old your body really is from a functional standpoint?

How Is Biological Age Calculated?

Thanks to advances in longevity medicine, doctors can assess biological age via a blood sample. The most advanced biological clocks are based on epigenetics. Our partner, Tru Diagnostics, uses the Dunedin Pace of Aging as well as telomere length and DNA methylation to calculate biological age. 


Epigenetics plays a crucial role in determining biological age. It refers to the study of heritable changes in gene expression or cellular traits that occur without alterations to the underlying DNA sequence. It explores the dynamic modifications and molecular mechanisms that influence gene activity and can be influenced by factors such as environment and lifestyle. Epigenetic modifications, including DNA methylation (more on that below), histone modifications, and non-coding RNA molecules, can affect gene expression patterns and contribute to various biological processes, including aging and disease susceptibility. 

Telomere Length

Just as the plastic caps of shoelaces prevent fraying, telomeres are like the caps of DNA that protect precious genetic information from damage. Without telomeres, cells would prematurely die or be unable to perform critical functions. This is why telomeres are considered the epigenetic clock of every cell in the body.

Numerous studies suggest that regardless of the type of disease, an underlying cause is shortened telomeres. 

“Although … disorders seem to be clinically diverse, collectively they comprise a single syndrome spectrum defined by the short telomere defect,” says a study in Nature Reviews Genetics

However, new research reveals that excessively long telomeres may also cause biological aging. A May 2023 study published in the New England Journal of Medicine revealed long telomeres are linked to cancer and the blood disorder clonal hematopoiesis of indeterminate potential (CHIP). 

Like most things, the optimal telomere length may be in the Goldilocks zone: just right. 

DNA Methylation

Despite the conventional wisdom that telomere length is the best indicator of biological age, DNA methylation may be superior to telomere length for assessing the aging process. 

“DNA methylation data is a more accurate marker of age than telomeric data and was able to predict time to death, time to coronary heart disease, and time to congestive heart failure more accurately than traditional telomere measurements,” says a research review article in Aging Medicine

When strands of DNA become methylated, it silences (“turns off”) the copying of DNA instructions (gene transcription). When DNA cannot be copied, it prevents cellular repair and division, leading to cellular death. 

To many people, DNA methylation is an esoteric concept. When you’re stuck in traffic and smell car engine exhaust, you’re probably not wondering if exposure to toxic fumes will trigger DNA methylation. So what factors do we have control over that may lower biological age? 

Applying Biological Age

One fascinating aspect of biological age is that organs within the same body can have different biological ages. For example, if you drink lots of alcohol, your liver can have a higher biological age than your heart if you exercise regularly. 

But determining the exact biological age of each organ remains elusive for most people, despite advances in diagnostic testing, as doing so would likely require a biopsy. So, biological age is calculated from the biomarker scores determined by a blood test. 

The exciting thing about biological age testing is that it’s a new treatment paradigm that replaces the one-size-fits-all approach. Functional medicine physicians leverage these advanced biomarker signals to create personalized treatment plans that are more precise for that individual.

In this way, patients optimize for both healthspan and lifespan rather than merely a longer lifespan. In other words, lowering your biological age may result in enjoying living more healthy years rather than just focusing on at which age you’ll die. 

Would you rather live to 85 free of disease or 100 suffering from a chronic illness for the last few decades of your life? Or better yet, suppose you’re 55 … wouldn’t it be ideal to live to 100, thriving with a healthspan of 45 more years? This is the potential of biological age optimization through the functional medicine paradigm.

Interested in learning about TRT? Find out more from Opt Health!

Chronological Age vs. Biological Age 

“It is becoming evident that the aging process is much more malleable than we used to think,” says a review in Experimental Physiology

Through the nascent field of epigenetics, we have discovered that we have more influence over how we age than we previously thought. Genetics do not entirely influence how long we live (chronological age). 

Instead, lifestyle interventions and environmental factors—prime epigenetic influencers—play a significant role in aging. This is the essential difference between chronological age and biological age. 

“Biology has established that there is almost certainly no fixed program for aging, which is caused instead by the lifelong accumulation of damage,” writes aging expert and author of The End of Age, Professor Thomas Kirkwood in Experimental Physiology. 

Kirkwood is quoted in Longevity Technology, “Aging is neither inevitable nor necessary.” What Kirkwood is implying is that cells could theoretically evolve to survive indefinitely. 

Kirkwood also suggests that advances in biological aging therapies continue to evolve, shattering the commonly-held belief that aging is an evolutionary imperative. 

While we may never be able to change our chronological age, and immortality still eludes us, we can decrease our biological age through individualized programs supervised by anti-aging expert physicians and lifestyle modifications (more on this below). 

What Affects Biological Age? 


You’ve heard about the longevity benefits of a Mediterranean diet. But the Southern European Atlantic diet (aka “Atlantic diet”) “could promote healthy aging by means of epigenetic mechanisms,” says a 2022 study in Advances in Nutrition

People who eat an Atlantic diet (such as Portuguese coastal villagers) have a higher life expectancy and enjoy a long healthspan. This is because the foods they eat are “enriched with nutrients of high biological value, which, together with its cooking methods, physical activity promotion, reduction in carbon footprint, and promoting of family meals, promote these positive effects on health.”

External Environment 

It’s not all doom and gloom when it comes to the environment. Compared to 1970 vehicle models, new cars, SUVs, and pickup trucks are roughly 99 percent cleaner for common pollutants (hydrocarbons, carbon monoxide, nitrogen oxides, and particle emissions), according to the Environmental Protection Agency (EPA). Yet, we don’t live in hermetically-sealed environments; we are still exposed to toxins on several fronts, which may lower biological age.

“Evidence suggests that environmental exposures, including but not limited to metals, air pollution, endocrine-disrupting chemicals, and noise, may accelerate biological aging,” says a study in the Italian journal La Medicina del Lavoro. 


You don’t have to be a professor of epigenetics to know that exercise may help lower biological age. But how? According to research, exercise slows the decline in telomere length and positively influences DNA methylation


Unsurprisingly, severe stress, such as a death in the family, a breakup, job loss, or moving residences, causes an increase in biological age. The good news is that new research published in Cell Metabolism suggests that the biological aging from the stressor is reversed when recovery from stress occurs. 

This led the researchers to conclude that unlike chronological aging, which is a linear trajectory, biological aging “is fluid and exhibits rapid changes in both directions.”

Sleep Habits 

In a peer-reviewed study titled “Sleep and Biological Aging,” the researchers propose that the molecular underpinnings of poor sleep quality lead to “altered metabolism [that] promotes damage, failure in repair and restoration machinery, leaving lasting impacts on cellular health, telomere loss, cellular senescence (when cells age but do not divide nor die, promoting the release of inflammatory chemicals), and ultimately system failure.” 


According to CDC data, in 2021, approximately 12 out of every 100 adults in the U.S. were regularly smoking cigarettes, which translates to 28 million smokers. In a 2019 study published in Scientific Reports, artificial intelligence (AI) was used to predict biological aging using blood biochemistry and cell counts from samples of nearly 150,000 smokers. 

Unsurprisingly, smokers demonstrated a higher aging ratio, and both male and female smokers were predicted to be twice as old as their chronological age compared to nonsmokers. 

How To Reverse Your Biological Age 

As mentioned, biological age is not a linear process. Instead, the underlying mechanisms that determine cellular aging can wildly fluctuate, not just year to year but month to month, week to week, and even daily. 

The easiest way to lower your biological age is to lead a healthy lifestyle: 

Opt Health and Biological Age 

Modifying their lifestyle seems impossible for some people, so professional guidance is needed. 

Opt Health provides personalized solutions for individuals looking to lower their biological age and increase their healthspan with world-class medical professionals and a cutting-edge technology platform. The result is enhanced health, wellness, strength, and sexual vitality.

Whether you need a helping hand in reversing your biological age or want to ensure that you’re functioning at your full potential, Opt Health is a leader in longevity medicine, using real-time methylation data, the latest in diagnostic technology, wearable devices, and more.

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