Is It the Most Important Number in Longevity?

A few years ago, almost no one had heard the term biological age. Today it is a common term among people looking to live more healthfully. A large part of that shift traces back to Bryan Johnson, the tech entrepreneur who has spent millions of dollars trying to slow his own rate of aging and shares the results publicly for anyone to follow. He also helped launch the Rejuvenation Olympics, a global leaderboard where participants compete to see who is aging the slowest, measured through DNA methylation testing. All of it makes for a compelling headline, though it tends to skip past a more useful question: should you actually care about your biological age?

At Argentis, we think the answer is yes, as long as you understand what the number is measuring and where its blind spots are. Biological age can be one of the more valuable tools in a longevity program, a way to check whether the work you’re putting into your health is actually landing.

Why Is Everyone Talking About Biological Age?

A decade ago biological age lived almost entirely inside research labs, so it’s worth asking what pulled it into everyday conversation. The clearest catalyst is Bryan Johnson, who turned his own body into a public experiment called Blueprint and spends a reported sum north of two million dollars a year measuring and adjusting nearly everything about how he lives. His results have become almost as recognizable as he is, and for a lot of people they offered a first real glimpse of the idea that aging might be something you can track and influence rather than simply endure.

Around the same time, the Rejuvenation Olympics gave that pursuit a scoreboard, taking something private and turning it into a public competition people could rank and share. Social media carried the clips far and wide, the broader longevity movement gave people a reason to care about how well they age rather than only how long, and the testing itself grew steadily cheaper and easier to order from home. 

What Is Biological Age?

Father Time marches on, and it can feel as though aging simply happens to us on a fixed schedule. Chronological time is the most common way to look at aging, but it seems inadequate considering that all people do not age in exactly the same manner over time.

Biological age tries to capture that difference by estimating how old your body appears based on measurable biomarkers. There’s real wisdom in the old saying that you’re only as old as you feel, and biological testing takes it a step further by paying attention to how old your cells feel. It reads the wear and tear accumulating inside you over the years, the running total of genetics, lifestyle, and environment all playing out at once. 

For a long time we assumed that story was written mostly by our genes, but a growing body of research now points to lifestyle carrying far more of the weight than we once credited. That turns out to be the encouraging part of the picture, because a number shaped by daily choices is a number you have some real power to move.

There Isn’t One Biological Age

There are actually numerous tests that look at different variable aspects of this complicated process of aging. Some tests read the chemical marks that accumulate on your DNA over time. Others study the story your blood chemistry is telling about inflammation, metabolism, and organ function. 

Some measure what your body can physically do, from strength to balance to endurance, while others focus on individual organs, since your heart and your kidneys don’t necessarily age in step with each other. Still others rely on imaging, or hand the raw data to an algorithm and ask it to surface patterns a person might miss. Every one of these approaches has genuine merit, and every one of them carries real limitations.

What Tests Are Available?

If there’s no single answer, the practical question becomes which options exist and what each one does well. The table below lays out the tests you’re most likely to run into.

A few of these tests behave like speedometers, telling you how quickly you’re aging at this moment, while others act more like odometers, estimating how much wear has already accumulated. Some are built to predict long-term risk, and others simply gauge what your body can accomplish today. Each test has its own advantages. Which one you pick depends on which information is most useful to you right now.

Why Argentis Selected Our Approach

At Argentis we evaluate biological age testing against five criteria:

✓ Strong peer-reviewed validation, so the science holds up under real scrutiny rather than clever marketing

✓ Repeatable over time, because a result you can’t reliably reproduce can’t guide much of anything

✓ Sensitive to lifestyle change, so the effort you put in actually shows up in the number

✓ Easy to understand, so a report leaves you informed rather than anxious over a decimal point

✓ Useful for guiding real-world decisions, since meaningful action is the entire point

After using this approach, we lean into SystemsAge from Generation Lab as our core test. Here is a link to download a sample report, so you can see the detail it can show you.  Some of the other blood testing and performance testing we use, like the PNOE Vo2 max also provide their own biological age results.  So our clients will end up having access to a few different numbers.  What is key is not what any one number says, its what changes over time, and how to connect the dots between your lifestyle changes and what the data shows.  

This is the area Argentis is most focused on, closing the loop with our clients so they can see how the choices they make on their diet, sleep, exercise, supplements and even more advanced therapies like red light, hyperbaric chambers and even stem cells are impacting their cells.   

The Bottom Line

Biological age isn’t your destiny, and no single test can capture the whole of your health. It works best treated as a dashboard, a readout you can glance at to see whether your lifestyle is steering you toward better long-term health. Approached that way, testing can genuinely help you understand whether your habits are carrying you in the right direction, and the habits themselves will always matter more than the figure they produce.