Healthspan & lifespan

Over the last 120 years, human life expectancy has more than doubled. In 1900 the global average was around 32 years; today it's over 70, and in the EU it's above 81. That's one of the great achievements in history, and most of it came from clean water, vaccines, antibiotics, safer childbirth and better emergency care.

But we added years faster than we added healthy years. And that gap is what this chapter, and this course, is about.

Two different numbers

Lifespan is how long you live. Healthspan is how long you live in good health: independent, free of serious chronic disease, able to do the things that make your life yours.

Depending on how "good health" is measured, the gap between the two is somewhere between ten and nearly twenty years. Eurostat estimates that people in the EU can expect around 62–63 years without a long-term limitation on their daily activities, out of a life expectancy of about 81. For many people, the last one to two decades of life involve some combination of chronic illness, medication, reduced mobility and dependence on others.

What fills those years

Most people in Europe don't die suddenly. They die slowly, from a small number of chronic diseases that develop over decades:

• Cardiovascular disease, heart attack and stroke, the leading cause of death in the EU, responsible for around a third of all deaths.
• Cancer, responsible for roughly a quarter.
• Neurodegenerative disease, above all dementia, the fastest-growing cause of disability in older age.
• Metabolic disease, type 2 diabetes and fatty liver, which quietly raises the risk of all three above.

Add frailty, falls and the loss of muscle and bone, and you have most of what goes wrong in the last decade of life. The encouraging part: these conditions share the same root causes, and the same handful of habits push all of them back.

Compressing the bad years

In 1980, the Stanford physician James Fries proposed an idea he called the "compression of morbidity". If we can delay the onset of chronic disease faster than we extend life itself, then the period of illness at the end of life shrinks. People live long, stay well, and decline quickly at the very end.

That's the real goal of longevity. Not to live to 120, but to make your 70s look like your 50s and your 80s look like your 60s. Research on people who live past 100 supports it: the very oldest tend to develop serious disease much later than average, and spend a smaller share of their lives unwell.

How much of this is in your hands?

A great deal. In a 2018 analysis of more than 120,000 people followed for up to 34 years, adults who kept five low-risk habits (never smoking, a healthy weight, at least 30 minutes a day of moderate-to-vigorous activity, a good-quality diet and moderate or no alcohol) lived around 14 years longer as women and 12 years longer as men, from age 50, than those who kept none. A follow-up study found most of those extra years were free of cancer, heart disease and type 2 diabetes.

Genes matter too, but less than most people think. Estimates of how much of lifespan is inherited range from around 25% down to under 10%. For most of us, daily habits carry more weight than family history, although family history is still worth knowing, and the Personalised longevity chapter covers how to use it.

Think about the end first

Here's an exercise worth ten minutes. Picture yourself at 85. Write down five things you want to still be able to do. Common answers: carry my own shopping up the stairs. Get down on the floor and back up to play with grandchildren. Travel on my own. Lift a suitcase into an overhead locker. Remember the names of the people I love.

Then work backwards. Every one of those tasks requires strength, balance, cardiovascular fitness and a healthy brain, and every one declines with age. If you want to be able to lift 10 kg at 85, you need to be a good deal stronger than that at 60, because you will lose some along the way. Your training and habits today are the reserve you'll draw on later.

Key numbers
10–20 years: the typical gap between lifespan and healthspan, depending on how it's measured.
~1 in 3: EU deaths caused by cardiovascular disease.
12–14 years: extra life expectancy at 50 linked with five low-risk habits.

This week

• Write down the five things you want to be able to do at 85. Keep the list somewhere you'll see it.
• Ask your parents or older relatives what they wish they had done differently in their 40s and 50s.
• Count how many of the five low-risk habits you already keep: not smoking, a healthy weight, 30 minutes of daily activity, a good diet, little or no alcohol.

In the journal

Your why, on page 14 of the journal, is where your 85-year-old self goes.

Sources: Fries, New England Journal of Medicine 1980 · Li et al., Circulation 2018 · Li et al., BMJ 2020 · Andersen et al., Journals of Gerontology 2012 · Ruby et al., Genetics 2018 · Eurostat, Healthy life years statistics · Eurostat, Causes of death statistics