Longevity — the science of aging more slowly

Say the word longevity and most people picture extreme old age: someone who made it to ninety but spent the last fifteen years surrounded by illness and pills. The science of aging sees it differently. Its goal isn't to add extra years of frailty, but to keep you vigorous and independent for longer, and to push disease closer to the very end.

A century ago, talk of "extending life" belonged to alchemists and charlatans. Today it's a serious field of science: aging is studied at the molecular level, it has been traced to specific mechanisms, and — most importantly — it turns out the pace of aging depends largely on us. According to twin studies, heredity explains only about 20–25% of the differences in lifespan. The rest is lifestyle, habits and environment — in other words, the things you can change.

This article is the introduction to our "Longevity guide." We'll go through it in order — no myths and no promises of eternal youth: how "living long" differs from "living healthy," why the body ages at all, what actually slows the process down, and how to measure your own pace of aging starting today.

A long life and a healthy life aren't the same thing

There are two different "spans," and confusing them is the cardinal mistake. Lifespan is how many years a person lives in total, from birth to death. Healthspan is how many of those years they spent healthy, active and free of dependence on others. The World Health Organization tracks the second measure separately and calls it "healthy life expectancy" (HALE).

And the gap between these two figures, worldwide, averages about ten years. Over the past few decades medicine has become very good at extending life: intensive care, stents, and blood-pressure and blood-sugar drugs save people who once would have died. But those same years are often lived with disease already present. We've come to live longer — without living much longer in good health. The gap hasn't gone anywhere, and in some places it has even widened.

Picture two scenarios with the same 85-year lifespan. In the first, a person is vigorous until 70, then declines over the final 15 years. In the second, they stay active until 82 and pass away after a brief illness. Both lived the same number of years, yet the quality of those lives is incomparable. Longevity science aims squarely at the second scenario: not "hanging on longer," but compressing the period of frailty — getting sick later, for a shorter time, and more mildly.

This points to an important shift in thinking. Normally we treat diseases one at a time: the heart acts up, we see a cardiologist; blood sugar climbs, we see an endocrinologist. But heart attack, diabetes, dementia and many cancers share one common — and strongest — risk factor: age. By slowing aging itself, you can push back a whole cluster of diseases at once, rather than fighting each one separately after it has already arrived. That's why researchers increasingly talk not about "treating diseases" but about "slowing aging" as the smarter strategy.

Why we age, in plain terms

For a long time, aging was seen as a kind of "wear and tear" — like a car simply using up its mileage. The picture today is more complex and more interesting. In a major 2023 scientific review, researchers gathered everything known about aging and distilled it into twelve interconnected "hallmarks of aging." You don't need to memorize all twelve — it's enough to grasp the logic through a few of the key ones.

Cells wear out from dividing. The ends of our chromosomes carry protective "caps" called telomeres. Think of them as the little plastic tips on shoelaces that keep the laces from fraying. Every time a cell divides, its telomeres get shorter, and once the reserve runs out, the cell stops dividing. Some of these "spent" cells don't die — they turn into a kind of "zombie," known as senescent cells. They no longer do their job, but they don't leave either; instead they pump out inflammatory signals and effectively "infect" neighboring healthy cells with aging.

The cleanup and the power supply break down. Inside every cell is a waste-disposal system called autophagy. It breaks damaged proteins and organelles down into spare parts and recycles them. With age, this housekeeping works worse and worse, and the "garbage" piles up. At the same time, the cell's "batteries" — the mitochondria — start to fail: they produce less energy and more harmful byproducts (free radicals). Those radicals ramp up oxidative stress, which in turn damages the mitochondria and the telomeres themselves. The circle closes.

Metabolism goes off-key, and inflammation smolders. Cells gradually grow deaf to insulin's signal — a state called insulin resistance, and the first step on the road to type 2 diabetes. Meanwhile a faint, chronic inflammation smolders throughout the body for years; scientists gave it a fitting name, "inflammaging," a blend of inflammation and aging. It doesn't hurt and you can't feel it, but over decades it quietly damages the blood vessels, the brain and the joints.

From this picture follows a practical takeaway worth remembering: since aging has many causes and they're all tangled together, there simply can't be a single "anti-aging pill" in principle. No supplement fixes all twelve mechanisms at once. But nearly every one of them responds to the same ordinary, everyday habits — and those are worth talking about in more detail.

What really moves the needle on aging

Here the key is to get the priorities right, because that's exactly what people usually turn upside down. On social media, the loudest talk is about exotic supplements, "smart" gadgets and biohacking. What actually works, first and foremost, is the boring, long-familiar stuff. Let's sort it by strength of evidence — from the most solid to the most debatable.

The foundation is four habits with a strong evidence base. The first is movement. It may be the only intervention that benefits nearly all the hallmarks of aging at once: the heart, the blood vessels, the brain, metabolism, the muscles. And this isn't about marathons — a large analysis of data from hundreds of thousands of people found that even moderate activity like brisk walking is linked to roughly a 20–30% lower risk of premature death. The second is 7–9 hours of sleep: chronic sleep debt stokes inflammation and takes a toll on memory and metabolism. The third is a diet built on vegetables, legumes and whole grains, with less sugar and ultra-processed food; the best-studied pattern is the Mediterranean one, which in a large trial reduced the risk of cardiovascular events. The fourth is not smoking — one of the strongest "accelerators" of biological age; and the good news is that some of the harm is reversible over time.

Important, but harder to measure. This is where the mind and social ties come in. Chronic stress and loneliness measurably speed up aging, while close relationships, a strong community and a clear sense of purpose slow it down. The evidence here is serious; such factors are simply harder to "weigh" in a study than miles walked. In the same category are intermittent fasting and moderate calorie restriction: the mechanisms are elegant and the animal data are convincing, but in humans what's been shown so far is mostly an effect on weight and lab markers, not on lifespan itself.

Lots of hype, little evidence. These are the "anti-aging" supplements — NMN, resveratrol, berberine, various "senolytics" and the rest. They often have elegant mechanisms in a test tube or in mice, but as of today there's no convincing evidence they extend healthy life in humans. It's important to understand: "not proven" is not the same as "harmful" or "doesn't work." It means we honestly don't know — and it's certainly no reason to put supplements ahead of sleep and movement.

Can you check how fast you're aging?

Yes — and this is perhaps the most practical idea in the whole subject. Your calendar age ticks along the same for everyone, year after year. Your biological age moves at different speeds. Two people who are both 50 can differ "on the inside" by 15–20 years: one person's blood vessels, metabolism and inflammation look like a forty-year-old's, the other's like a sixty-five-year-old's.

The idea of measuring biological age isn't new, but it really came into its own over the past decade. Researchers learned to build "aging clocks" from ordinary blood tests and other markers — clocks that estimate how far ahead of, or behind, your calendar age the body is running. And unlike your date of birth, this number can be moved: it responds to changes in lifestyle. There are several ways to measure it:

• From blood tests. The PhenoAge model turns 9 routine blood markers (including inflammation, blood sugar, and liver and kidney function) into a single, easy-to-read biological age and risk estimate.
• Without lab tests. A quick estimate from height, weight and waist circumference — for when you don't have fresh bloodwork on hand but still want a ballpark figure.
• By individual systems. The age of your heart, blood vessels and brain — separate "clocks" show which system in particular is aging faster than the rest of the body.

There's an important nuance here: don't chase a single number and turn it into either a tragedy or a badge of pride. What matters far more is the trend — where you started and where you're heading as you change your habits. One measurement is just a snapshot in time. The meaning appears when you have several of them and can see the trajectory: heading down means you're on the right track.

Where to start: a plan for your first week

Theory without a first step is useless. The mistake most people make is trying to change everything at once — starting Monday, all at the same time: exercise, diet and sleep schedule. That burst of resolve usually fizzles within two weeks. The opposite works — one habit at a time, but for good. Here's a calm week-one plan to start with.

Frequently asked questions