What a leading geriatrician says about the rise of centenarians

The number of people reaching 100 is climbing faster than demographics alone can explain. In a recent interview, Dr. Olivier Guérin, a professor of geriatric medicine, said that while an aging population made some increase inevitable, the real surprise is the scale of it—pointing to genuine gains in longevity, particularly among women. He credits better medical care and broader improvements in quality of life.

But the core of his message is that longevity isn't just about luck or heredity. A landmark study he referenced shows that roughly a quarter of life expectancy is tied to genetics, another quarter to environment, and nearly half to personal behaviors: physical activity, diet, sleep, smoking, alcohol use, and maintaining a social life. "That's a very encouraging message," Guérin emphasises, "our way of life weighs more than our genetics."

Even though some families do boast several centenarians owing to hereditary predispositions, at a population level the single most potent lever available today remains health behaviors. The doctor also offered a glimpse into the patients he sees in hospital—often only when an acute event like a severe infection, stroke or heart attack strikes. The broader picture, he notes, is that many who reach 100 have managed to avoid heavy chronic illness for most of their lives.

Why lifestyle trumps genes—and what hospital data really shows

The 50% that's within our control

The idea that lifestyle choices account for around half of longevity is not just optimistic—it's actionable. Guérin’s breakdown gives individuals a clear mandate: exercise, nutrition, rest, substance use and social connection are the biggest dials we can actually turn. He acknowledges genetic predispositions but frames them as background noise against the signal of daily habits, especially when looking at the whole population.

What hospital data tells us about centenarians

Guérin cautions that the centenarians he encounters are a biased sample—they have landed in hospital because something went wrong. Yet the backstory that emerges is consistent: those who make it to 100 are typically not people who spent decades battling multiple chronic illnesses. Instead, they are individuals who remained relatively robust until a late-life crisis intervened. This suggests that compression of morbidity—living long and staying healthy until the very end—is partly achievable through the same lifestyle levers that extend lifespan in the first place.

The habits that give you the best shot at a long, healthy life

If nearly half of how long you live is shaped by daily choices, then small, consistent changes can have an outsized impact. Based on the determinants Guérin highlights:

  • Move regularly: aim for at least 30 minutes of moderate activity most days. Even walking or gardening counts.
  • Eat a balanced diet: focus on whole foods, vegetables, lean proteins and healthy fats while minimising ultra-processed items.
  • Protect your sleep: prioritise 7–8 hours of quality rest; treat it as health care, not lost time.
  • Cut back on smoking and alcohol: both are powerful, modifiable risk factors for the diseases that cut life short.
  • Stay socially connected: relationships and community engagement have a measurable protective effect against cognitive decline and premature death.