What is longevity?

Longevity is both a research field and an everyday goal, and in both the point is more healthy years rather than more years. Worldwide, life expectancy and healthy life expectancy sit close to ten years apart.^[2] The evidence for narrowing that gap is mostly ordinary prevention and everyday habits. The market around the word sells far more than that. As of October 2026, though, no completed trial has shown that its leading drug and supplement candidates prevent disease or extend life in healthy people.^{[16, 26]}

Longevity means long life, but in current usage the word carries more than a high age (the longevity glossary has the short definition). It now names a research field and a set of lifestyle decisions, both built around healthspan. That means the years someone lives without serious chronic disease or a lasting loss of independence. The plain phrase long life misses that extra layer: healthy years rather than years alone, measurable markers, and prevention rather than repair.

As a research field, longevity sits between two neighbours. Geroscience studies how the biological processes of ageing drive age-related diseases, while preventive medicine works on the clinical side, with early detection and risk factors. Longevity is used loosely as an umbrella over both, which makes the word handy in a headline and imprecise in a study.

Outside health, the word keeps its plain sense of long duration: the longevity of a career, a marriage or a washing machine. Close synonyms are long life, long-livedness and durability. The spelling trips people up as well, since it is longevity, not longetivity or longivity.

The spelling makes more sense once you know the word is Latin in origin: longus means long and aevum means lifetime. From longaevus, meaning long-lived, came late Latin longaevitas and finally English longevity. You say it [lɒnˈdʒɛvᵻti], with the stress on the second syllable and a soft j sound as in journalist rather than a hard g.

Lifespan is how many years someone lives, and healthspan is how many of those years pass without serious chronic disease or lasting limitation. Life expectancy, the third term, is a statistical one: the average number of years people of a given age can still expect to live. The distance between a long life and a healthy one is what the longevity debate is really about.

A study of 183 WHO member states measured that distance, and worldwide it grew from 8.5 years in 2000 to 9.6 years in 2019.^[2] It is calculated as life expectancy minus WHO's health-adjusted life expectancy, which counts each year of life by how healthy it was. The authors read the difference as years lived with disease or disability. It is larger where non-communicable diseases (the chronic kind, as opposed to infections) weigh more heavily.^[2]

The gap is not the same for everyone. Women's gap averaged 2.4 years wider than men's, and Germany had the widest difference between the sexes of all 183 states, at 3.6 years.^[2] Between countries, the United States came out worst at 12.4 years, almost three years above the global figure.^[2] The table lists the five largest gaps next to the worldwide value:

Source: analysis of 183 WHO member states.^[2]

Germany's own figures come from the Federal Statistical Office (Destatis). Life expectancy at birth reached new highs in 2025, at 83.6 years for women and 79.1 years for men.^[20] At the end of 2024, about 17,900 people aged 100 or older lived in Germany, more than four in five of them women.^[21]

Those records count years, though, not healthy years, and the gap in the table is the part longevity research wants to shrink. Researchers call that goal compression of morbidity: pushing the sick years into a shorter stretch at the end of life rather than adding years at the top. For the countries at the top of the table, it would mean fewer of the final years spent ill, whether or not life expectancy rises any further.

Three ideas run through longevity research, whatever the packaging: healthy years come before total years, genes and lifestyle both count, and evidence beats hype.

Healthspan before lifespan. The first idea is the goal behind compression of morbidity (fewer sick years at the end of life), which aims for the most functional years rather than the most years. It has a known weak spot, though, because there is still no single agreed way to measure healthspan, which makes studies hard to compare.^[1] Careful writing therefore says which definition it is using.

Genes and lifestyle both count. Heritability is the share of the differences between people that genes explain, not a share of any one person's lifespan. For lifespan, the answer depends heavily on how it is measured. A classic Danish twin study put it at about a quarter.^[3] A far larger family-tree analysis, which allowed for people choosing partners similar to themselves, found well below 10 percent.^[4] A 2026 study then removed deaths from outside causes such as accidents and infections from the older data. For this intrinsic lifespan it arrived at about 50 percent or slightly above.^[5] That last figure describes something narrower than the other two, which include those outside deaths, so the three are not directly comparable.

The range is wide, but even on the highest estimate close to half of the differences come from behaviour, environment and chance. Two US cohorts (groups of people followed over time) with more than 120,000 participants suggest what is at stake. The researchers carried the observed death rates forward in a life-table projection. At 50, women with all five low-risk factors had a life expectancy about 14 years higher than women with none. For men the difference was about 12 years.^[13] These are observational data, from watching people rather than from experiments, so they show a link rather than proof of cause.

The five factors were never smoking, a healthy body weight, regular activity, a high-quality diet and moderate alcohol intake.^[13] That last one has aged less well than the others: the German Nutrition Society concluded in 2024 that no amount of alcohol is safe and advises avoiding it.^[19]

Evidence over hype. The scientific frame is the twelve Hallmarks of Aging, updated in 2023: twelve linked processes, from DNA damage to chronic inflammation.^[6] Understanding such a process is a long way from showing that a treatment aimed at it keeps people healthy, and that step takes trials in people.

Demography sets a second limit, on how far lifespan itself can stretch. The longest validated life lasted 122 years and belonged to Jeanne Calment, who died in 1997. A 2018 challenge to her age was examined and rebutted by the original validators.^{[17, 22]} One analysis argues that the maximum reported age at death has plateaued at around 115 years since the 1990s, which would make 122 a statistical outlier.^[8] That paper is contested, though, because several technical comments dispute its method.

Demographers who studied the longest-lived populations reach a similarly sober conclusion. Unless biological ageing itself can be slowed, the chance of reaching 100 is unlikely to exceed 15 percent for women and 5 percent for men.^[7] Longevity escape velocity names the hope that medicine will one day add more than a year of remaining life expectancy for every year that passes. The same data cut against it, because gains in the longest-lived countries have slowed since 1990.^[7] On those numbers, radical life extension within this century looks implausible,^[7] so the realistic prize is more healthy years within a normal lifespan.

We group the everyday part of longevity research into six pillars: movement, nutrition, sleep, social connection, stress management and prevention. All six describe things you do rather than things you buy, from how you move and eat to how you handle stress and whether you use check-ups. That is also why no supplement appears among them.

Other sources count differently, and the Blue Zones literature, for example, names nine shared habits, the Power 9.^[27] The number is an editorial choice rather than a constant. We use six because each of these fields has a large long-term study or a meta-analysis (a pooled analysis of many studies) behind it. The 6 pillars in detail goes through them one by one. The order follows the strength of that data, not a priority for daily life.

Biological age is an estimate of how far ageing has progressed in the body, and different methods give different numbers. Chronological age, by contrast, simply counts birthdays. The best-known method is the epigenetic clock, which reads DNA methylation patterns: chemical tags on the DNA that shift with age. In 2013 Steve Horvath showed that these tags allow a surprisingly accurate age estimate across many tissues.^[14] Many more clocks have followed since, and they pick up different changes in health, so they are not interchangeable.

In practice that makes a single number an estimate, not a diagnosis. The methods are covered in the biological age guide. If you want to try one, we run a free age test and a photo-based face age estimate. Both are educational tools that return an estimate, and neither replaces a medical examination.

Blue Zones are five regions described as having unusually many very old residents.^[27] They are Okinawa in Japan, the Barbagia region of Sardinia, Ikaria in Greece, the Nicoya peninsula in Costa Rica and Loma Linda in California. The habits drawn from them sound familiar: constant everyday movement, a largely plant-based diet, close social ties and a reason to get up in the morning, among others.^[27] That summary comes from authors who work for Blue Zones LLC, a company with a commercial interest in the idea.^[27]

The age records behind those regions have been under scrutiny for years. The demographer Saul Justin Newman found that supercentenarians, people aged 110 and over, cluster with other record ages in particular places. Those are places where birth registration was patchy, poverty high and average life expectancy short.^[15] In the United States, such records fell by 69 to 82 percent once birth certificates were introduced.^[15] Reported birthdays also pile up on dates divisible by five, a pattern he links to clerical errors and pension fraud.^[15] His analysis includes Sardinia, Okinawa and Ikaria.^[15] It is a preprint, meaning it has not been peer reviewed, and it has been challenged, so it moved the debate without settling it.

The habits hold up better than the record ages, and the Blue Zones guide goes through both in full. Not smoking, regular movement and a good diet go with a longer life in large US cohorts,^[13] and strong social ties go with better survival.^[11] None of those studies tested the Blue Zones themselves, so we read them as support for the habits rather than for the regions' records.

Longevity is a heavily marketed word, so it helps to draw three boundaries: it is not a supplement programme, not anti-aging cosmetics and not one entrepreneur's protocol.

Not a supplement programme. Capsules are the most visible part of the longevity market, and for most of these products there is no human lifespan data. The most promising candidates, among them rapamycin, metformin and NAD+ boosters, rest mainly on cell and animal studies.^[16] Single compounds have their own guides, such as NMN and rapamycin. Human studies so far mostly measure surrogate markers: lab values such as blood sugar that stand in for real outcomes.^[16] Where a trial did look further, the results pull in different directions. In one trial in older adults, six weeks of mTOR inhibitors (the drug class of rapamycin) went with fewer infections in the following year. A larger phase 3 trial then missed its main goal.^[16] As of October 2026, no completed trial has shown that any of these candidates prevents disease or prolongs life in healthy people.^{[16, 26]}

The same caution applies to longevity shots, a term sometimes used for GLP-1 drugs such as semaglutide, whose data the guide on GLP-1 and longevity goes through. Semaglutide is approved as Ozempic for type 2 diabetes.^[28] As Wegovy it is approved for weight management in adults with a BMI (body mass index, weight relative to height) of 30 or more, or 27 or more with at least one weight-related condition.^[25] Neither is approved for ageing.

Rapamycin (sirolimus), metformin and semaglutide are prescription-only medicines in Germany (as of October 2026).^[24] Using them against ageing would be off-label, meaning outside their approved use, and belongs only under medical supervision, not in a self-experiment. Rapamycin suppresses the immune system, and in studies of people with age-related diseases, infections and blood lipids rose.^[26] Semaglutide should not be used during pregnancy.^[25]

Not anti-aging cosmetics. Anti-aging in retail usually means appearance: skin, wrinkles, hair. Longevity means function, which covers the cardiovascular system, metabolism, muscle and cognition. The two terms overlap in marketing, not in research.

Not the Bryan Johnson protocol. The US entrepreneur has documented an extensive self-experiment and did a great deal to popularise the topic. A single case without a control group is not a study design that generalises, so the project matters as a media phenomenon and not as evidence. The guide to longevity pseudoscience collects the signs of unsupported claims, which helps whenever a product page sounds more certain than its studies.

Longevity medicine is not a protected term and not a recognised medical specialty. In practice the phrase describes what clinics and practices sell: many tests, lab panels, scans and lifestyle coaching in one package, usually paid out of pocket. There are courses and certificates in it, but they are private, not recognised specialist training.

There is no defined treatment called a longevity therapy either, so we sort what is sold under that label into three groups. The first is the prevention that normal health care already offers: blood pressure, blood lipids, blood sugar, vaccination status and cancer screening. The second is testing with no shown benefit in people without symptoms. The third is the experimental side, from infusions to off-label drugs (used outside their approved purpose), whose benefit and risks in healthy people have not been shown.

Prevention, the first group, is also the part with the best evidence, and it is plain. Expert consensus treats LDL cholesterol as a cause of atherosclerotic disease (plaque build-up in the artery walls), based on genetic, population and clinical studies.^[12] The link between fitness and a lower risk of death is also well documented.^[9] Both are standard medicine rather than longevity medicine. In Germany statutory insurance already pays for a check-up with blood lipids every three years from 35, a useful baseline to hold any self-pay package against.^[18]

We recommend no specific service here, but three guides cover the practical side of such packages:

• what a clinic check-up typically costs: longevity clinic costs
• which offerings are usually self-funded: self-pay longevity
• where non-medical practitioners come in: practitioners and longevity

You can start on longevity without buying anything, because most of the evidenced part costs little or nothing. The visible part of the field is tests, capsules and subscriptions, which gives it a price problem the evidence does not share. Three routes come at no extra cost:

Meet people. Cities across our network run regular meetups where researchers, clinicians and curious people end up in the same room. Entry is free, and the list of cities sits under chapters. A meta-analysis (a pooled analysis) of 148 observational studies linked stronger social relationships to better survival, an association the authors call comparable to well-established risk factors.^[11] No trial has shown that a meetup visit adds years to anyone's life, but meeting people costs nothing.

Run the numbers. Our tools are free and need no account. They range from an energy-requirement calculator to a VO2max estimate (how much oxygen your body can use during hard exercise) and a grip-strength check. They replace no diagnostic work, but they put your own numbers in context.

Use the check-ups you already have. In Germany statutory health insurance pays for a general health check once between 18 and 34 and every three years from 35. It covers your history, a physical examination with blood pressure and a check of your vaccinations. From 35 it also includes blood lipids such as cholesterol, fasting blood sugar and a urine test. Before 35, blood tests are done only with risk factors such as a family history, obesity or high blood pressure.^[18] From 35 there is also a one-off test for hepatitis B and C,^[18] and skin cancer screening every two years.^[23]

All of this is the status as of October 2026. The G-BA, the body that decides what statutory insurance covers, has started a review of age limits, frequency and content, due by the end of 2027.^[23] Many other countries fund something comparable, so it is worth checking what yours covers. That check-up already covers part of the sixth pillar, prevention, and anything beyond it is a conversation with your doctor. If you are eligible, booking it is a reasonable place to start.^[18]