Chronological Age vs Biological Age + 6 Important Factors That Affect Aging

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Aging is an inevitable process. We all know how quickly time can pass, and before you know it, it’s your next birthday, and a whole year of your life has flown by. 

Though our lives have ups and downs, almost all of us can agree on one thing: we would like to live longer so that we have more time on earth to experience the wonderful gift of life.

Although aging is certainly a complex, multifactorial, and inescapable process, we often only think of the physical and cognitive ramifications of aging on a systemic level. 

We might notice hair loss or that our hair is turning gray, a decrease in muscle mass (sarcopenia), wrinkles in the skin, seemingly slower brain function, and worsening memory. But what about chronological age vs biological age?

However, aging actually begins at the cellular level, and what we are experiencing in terms of the gradual decline of our body systems overall is just the accumulation and manifestations of the changes that are happening in our cells.

This is essentially what is meant by biological aging: biological aging refers to the health of your cells. So what is the difference between chronological age vs biological age?

In this article, we will look at: 

  • Chronological Age vs Biological Age: What Is Chronological Age?
  • Chronological Age vs Biological Age: What Is Biological Age?
  • What Factors Affect Biological Age?
  • How Is Biological Age Determined?

Let’s jump in!

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Chronological Age vs Biological Age: What Is Chronological Age?

Chronological age refers to your age in years or how long you have been alive. It is the way that we typically define our age when someone asks, “How old are you?“

Chronological age is measured in years and is determined by subtracting the year you were born from the current year.

For example, if it is 2023 and you were born in 1973, your chronological age is 50 years old.

Although chronological age can be useful in certain circumstances, your chronological age does not necessarily reflect how your body is actually aging on a cellular level.

Two people who were born on the same day in the same year might have a very different biological age, yet they have the same chronological age.

The 30th day on a calendar circled in red marker.

Chronological Age vs Biological Age: What Is Biological Age?

The principle behind biological aging vs chronological aging is that our body accumulates “damage“ to various cells, tissues, and systems of the body as we age.

The health or state of your cells or tissues on a physiological level is reflected in your biological age.

For this reason, biological age is also sometimes referred to as functional age or physiological age.

Although your chronological age will have an effect on your biological age, there are other factors that can affect your biological age vs chronological age other than just the number of days you have been alive on Earth.

What Factors Affect Biological Age?

The factors that can affect your biological age include the following:

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#1: Your Chronological Age

Although there are differences between chronological age vs biological age, and the number of years you have lived is not the sole determinant of the relative age of your cells and tissues, there’s no escaping the fact that your chronological age does play some role in your functional age.

In other words, if you are 60 years old, even if you have taken excellent care of your body and have the best diet and lifestyle habits, your cells are not going to reflect the same “youthfulness“ or health status of a healthy five-year-old.

#2: Genetics

Some portion of the aging process has a genetic component. 

Some people are at a higher risk for certain chronic diseases that will accelerate biological aging vs chronological aging, or your inflammatory and anti-inflammatory pathways might be more or less sensitive, which can either accelerate or slow down biological aging.

A variety of health foods such as fish, oil, nuts, and vegetables.

#3: Your Diet

Studies suggest that your diet can have a significant effect on your biological age. 

A diet high in nutritious foods, such as vegetables, fruits, lean proteins, eggs, nuts, and seeds, can lead to a younger biological age vs chronological age. 

Foods that are high in antioxidants and polyphenols, such as vegetables, fruits, nuts, and green tea, can counteract the deleterious effect of free radicals.

In this way, if your diet is rich in antioxidants, your cells and tissues will be subject to less oxidative stress, which can protect against premature biological aging.

On the other hand, if you regularly consume a lot of processed foods, added sugars, alcohol, artificial sweeteners, fried foods, trans fats and industrial oils, and excessive salt, you can accelerate biological aging.

Two people powerwalking in a park.

#4: Your Exercise Habits

Getting consistent aerobic exercise and strength training improves the health of your tissues and cells, decreases inflammation in the body, decreases cortisol levels, helps manage weight, and reduces the risk of chronic diseases.

If you are consistently meeting the physical activity recommendations set by the Centers for Disease Control and Prevention and the British Heart Foundation, you will likely have a younger biological age vs chronological age compared with an age-matched pier that is sedentary.

Those recommendations are to accumulate either 150 minutes of moderate-intensity aerobic exercise or 75 minutes of vigorous-intensity cardio exercise per week.

#5: Your Lifestyle 

Lifestyle habits such as how much sleep you get, chronic stress levels, smoking, and alcohol and drug use all affect your biological age and the health of your cells and tissues. 

Exposure to pesticides and chemicals can increase free radical production and cause oxidative stress, which will increase your biological age vs chronological age.

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#6: Your Overall Health

The presence of certain diseases can increase your biological age relative to your chronological age.

For example, if you have obesity, hypertension, metabolic syndrome, or type 2 diabetes, the cells and tissues of your body will be under additional strain that will accelerate biological aging vs chronological aging.

Given the aforementioned factors, let’s look at an extreme example of how two people may have a different chronological age vs biological age.

Imagine that subject A is a 30-year-old man who smokes two packs of cigarettes per day, works a sedentary job and does not exercise, and eats fast food and takeout most of the time. He is overweight and has high blood pressure, and works a stressful job, so he only gets about 5 to 6 hours of sleep per night.

A white-bearded man exercising.

Subject B is also a 30-year-old man, so he has the same chronological age as subject A.

However, Subject B has a normal body weight and follows a balanced Mediterranean diet. He does not smoke and exercises five days a week for 40 minutes. 

He is also relatively active during the day and manages his stress through mindfulness meditation and martial arts. He does not have any health conditions and generally sleeps about 7 to 8 hours per night.

Although both of these men have the same chronological age, the disparity in their chronological age vs biological age may be quite stark.

Subject A will have a biological age that well surpasses his chronological age. From a physiological standpoint, his cells may reflect the health and longevity of someone who is 50 or 60 years old. 

On the other hand, Subject B might have a younger biological age vs chronological age, given how well he takes care of himself. He may have the physiological age and health status at the cellular level of someone who is in their early 20s.

Therefore, the biological ages of our two subjects may be upwards of 30 or 40 years apart.

Two people running on a fall day.

How Is Biological Age Determined?

There are certain markers that can help determine your biological age, namely DNA methylation and telomere length.

DNA methylation is thought to play a significant role in the aging process and be an indicator of biological aging. Methylation is a biochemical process in which a methyl group is added to a biochemical molecule, in this case, DNA.

DNA methylation essentially turns genes “on” or “off” so that they are either expressed or dormant, and DNA methylation has been associated with the aging process and age-related degenerative diseases.

Telomere length is thought to be correlated with biological aging.

Telomeres are the proteins found at the ends of chromosomes, which are long strands of DNA that contain the genetic information for your cells.

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The function of telomeres is to help protect your strands of DNA from damage so that the chromosomes can replicate properly during cell division.

As we age, the length of the telomeres at the end of the chromosomes decreases so our telomeres shorten. The shorter your telomeres, the older your biological age, regardless of your chronological age.

There are a number of things you can do to improve your biological age or “reverse the clock“ on the age of your cells by preserving or lengthening telomeres. 

Examples of lifestyle factors that can slow down the aging process and protect telomere length include following a Mediterranean or plant-based diet, eating foods rich in antioxidants, eating more fiber, exercising regularly, taking vitamin D supplements, and decreasing stress.

If you are looking into adjusting your eating habits and decreasing your biological age, check out our diet guides for some healthy ideas.

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Photo of author
Amber Sayer is a Fitness, Nutrition, and Wellness Writer and Editor, as well as a NASM-Certified Nutrition Coach and UESCA-certified running, endurance nutrition, and triathlon coach. She holds two Masters Degrees—one in Exercise Science and one in Prosthetics and Orthotics. As a Certified Personal Trainer and running coach for 12 years, Amber enjoys staying active and helping others do so as well. In her free time, she likes running, cycling, cooking, and tackling any type of puzzle.

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