How Do We Know if We’re Really Slowing Down Aging?

Longevity research has a measurement problem.

If a new drug, diet or exercise program is supposed to slow aging, the most convincing test would be simple: follow people for decades and see whether they remain healthier longer.

The problem is that nobody wants to wait that long for an answer.

So researchers have increasingly turned to biological-age tests, including so-called epigenetic clocks that look for chemical changes in DNA associated with aging. In theory, if an intervention makes one of those clocks move more slowly, scientists might be able to tell within months or years whether it’s affecting the aging process.

But there’s a complication.

Different clocks don’t always respond to the same intervention in the same way.

A recent analysis in Nature Medicine examined dozens of human intervention studies and more than 100 DNA-methylation biomarkers to see which ones actually changed when people underwent treatments thought to influence aging. Some responded consistently. Others barely moved at all.

That matters because biological age is increasingly being treated as something we can measure, track and even improve. But a number is only useful if researchers understand what it’s measuring and whether a change in that number predicts something meaningful later.

The new analysis found that some biomarkers were more responsive to interventions involving diet, exercise and certain medications. It also reinforced something researchers are still working through: no single test appears to capture the entire aging process.

That may sound like a technical problem.

It’s also a fundamental one.

Before we can confidently say that something slows aging, we need a reliable way to tell that aging has actually slowed.

For now, the science of extending healthy life may be advancing faster than our ability to measure exactly what that progress means.

Source: Nature Medicine, “Responsiveness of Epigenetic Aging Biomarkers to Longevity Interventions in Humans” (2026).

Longevity

The Long Game
One small thing for a longer life

Try This

This week, write a short note to someone and mail it.

Not an email. Not a text. A physical card or a folded piece of paper, in an envelope, with a stamp.

Research on gratitude letters has found that people often underestimate how much a written expression of appreciation will mean to the person receiving it. Writers tend to worry about finding the right words or making the exchange awkward. Recipients usually care much more about the warmth of the gesture.

The note doesn’t need to be long.

Pick someone. Think of something specific you appreciate about them. Five sentences is enough.

Then put it in the mail.

The small effort involved may be part of what makes it feel different from a message that disappears into the day.

Small acts of connection are one piece of a bigger picture. The Worthyest Longevity Index measures six factors that shape how well we age in 4 minutes. Yours, personalized.

Get my score →

The Curiosity Edit

Today’s Insight: Future of Medicine

Gene Editing Could Replace a Lifetime of Medication, but There’s a Catch

Some new treatments are being designed to work for years, or even decades, after a single intervention. That promise comes with a difficult question researchers are only beginning to confront: what happens if a treatment meant to last can’t easily be changed later? Read the full story here.

Modern Living:

Decision-Making & Psychology

Why We Delay Important Decisions

Some decisions become harder the longer we leave them unresolved. Psychologists explain why uncertainty can make postponing a choice feel easier in the moment, even when the decision itself doesn’t go away. Read the full story here.

Health & Wellness

What Healthy Aging Looks Like in Practice

Protecting long-term health often comes down to how we treat the brain, the heart, and the routines that shape both over time. This collection looks at a neurologist-backed approach to brain health, how nighttime light exposure may affect cardiovascular risk, and the habits longevity experts personally avoid.

Neurologists Say This Is 1 of the Best Ways to Protect Your Brain as You Age
Brain health is often treated as something separate from the rest of the body, but neurologists increasingly argue for a broader view. One familiar health strategy may have more relevance to cognitive aging than many people realize.

Just This Much Light in Your Bedroom at Night Could Affect Your Heart, Says Research
Even modest nighttime light exposure may influence the body in ways that extend beyond sleep quality. New research raises questions about how much light is enough to affect cardiovascular health.

Longevity Experts Reveal the 6 Things They Personally Never Do
Experts who study aging often focus as much on what they avoid as what they recommend. Their personal habits offer a practical look at the behaviors they consider least helpful for staying healthy over time.

The Conscious Plate:

Food, Nutrition & Elevated Living

Simple Ways to Eat for Comfort, Aging, and Better Nutrition

Small food choices can support digestion, healthy aging, and a more balanced diet without requiring major changes. This collection looks at drinks that may calm an upset stomach, smarter snack choices for aging well, and fiber-rich foods that go beyond the usual beans.

Drinks Experts Recommend to Soothe an Upset Stomach
When your stomach feels unsettled, what you drink can make a noticeable difference. Experts point to several options that may be easier to tolerate and more soothing than your usual beverages.

The Best Snacks for Healthy Aging, According to Experts
The right snack can do more than bridge the gap between meals. Experts highlight choices that can help support nutrition needs that become more important with age.

6 Foods Besides Beans That Can Help Boost Your Fiber Intake
Beans get much of the attention when fiber comes up, but they’re far from the only option. Several familiar foods can help increase your intake while bringing more variety to meals and snacks.

Final Note

This is what we leave you with. A thought to end the day, carry in your pocket, or come back to later. Nothing big. Just something to reflect on.

The Table Next to Ours

Nothing makes a restaurant’s food look more appealing than seeing it delivered to the next table.

A menu asks us to imagine. The plate arriving nearby settles the question.

Suddenly the thing we barely considered ordering looks like exactly what we should have chosen.

Sometimes envy arrives one table at a time.

Pass It On

Sometimes a thought, an idea, or a perspective connects at just the right time. If something here feels like it might resonate with someone you know, share it with them.

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