What it means
Lifespan is the total number of years lived. Healthspan is the number of those years spent healthy, independent and free of major chronic disease. The difference — sometimes called the "sickspan" — is the period at the end of life spent with illness or disability.
Maximum human lifespan has barely moved in a century: the oldest verified person reached 122 in 1997 and no one has beaten it. Average lifespan has risen enormously, mostly from fewer early deaths. Healthspan has risen more slowly, which is why the gap has widened.
Why it matters for longevity
Nearly everything you can do — train, sleep, fix your metabolic markers, keep muscle — moves healthspan with good evidence and lifespan with weaker evidence. Nearly everything sold as a lifespan extender — rapamycin, NMN, senolytics — has lifespan data in mice and no lifespan data in humans. Aim at healthspan and the lifespan follows as far as it is going to.
What the evidence says
The 2024 analysis by Olshansky and colleagues in Nature Aging argued that life-expectancy gains have slowed sharply in the longest-lived countries since 1990, consistent with a biological ceiling. Meanwhile the global burden-of-disease data show the healthy-life-expectancy gap at roughly nine years in Europe and the US, and widening.
On the modifiable side, fitness is the standout: in Mandsager 2018 (122,000 adults, treadmill-tested), each step up in fitness category was associated with lower all-cause mortality, with no upper limit found. The same cohort data link fitness to fewer years of disability before death.
How to measure or use it
You cannot measure either number ahead of time, so you track the proxies. The biological-age clocks try to estimate where you sit; the physiological markers — VO2max, grip, ApoB, HbA1c — are what actually move the prediction.
- Set targets in the healthy-years column: a VO2max in the top quartile for your age, lean mass held through your fifties, a metabolic panel in range.
- Treat any product that quotes a lifespan number for humans as a red flag; no such trial exists.
Related
- What is healthspan? — the long version
- VO2max and longevity — the single strongest predictor
- The longevity drugs — where the lifespan claims come from
Frequently asked questions
Has anything been shown to extend human lifespan?
Not in a trial. The evidence for longer life in humans is observational: fit, lean, non-smoking people with good metabolic markers live longer. Drugs extend lifespan in mice; the human trials measure surrogate markers.
How big is the healthspan gap?
Around nine to twelve years in most high-income countries, depending on the definition used.
Which should a protocol target?
Healthspan. It is measurable through its predictors, it responds to intervention within months, and it is the part you will actually notice.
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