In 2014, then-57-year-old bioethicist Dr. Ezekiel Emanuel wrote an infamous essay titled, “Why I Hope to Die at 75” for The Atlantic. His argument boiled down to this: it’s not worth living as long as humanly possible if those efforts yield extra decades defined by disease and poor health, which data suggest is the fate awaiting many people in the U.S.

Nearly a decade later, neither Emanuel’s mind nor the statistics have changed much. Emanuel still says he plans to stop most life-extending medical care once he reaches age 75, though he’s healthy enough that he expects to live longer naturally. And there is still a yawning gap between the average number of years someone born in the U.S. can expect to live—77.5, according to a new federal estimate for 2022—and the number of years they can expect to live in full health: 66.1, according to the World Health Organization’s (WHO) latest calculations.

Experts often refer to this chasm as the gap between “lifespan” and “healthspan.” And, increasingly, they are focusing on the latter as the right measure of longevity. “It’s great to live to 100,” says Tim Peterson, CEO of Healthspan Technologies, a startup focused on healthy aging—but less so “if you live the last 30 years in poor health.”

The pandemic and rising rates of suicide and drug overdoses contributed to a recent multi-year drop in U.S. life expectancy that only reversed in 2022, when fewer COVID-19 deaths led to a recovery of about one year of projected lifespan. But even with the recent dips, U.S. life expectancy has risen considerably over the last century, from 59.6 years for those born in 1922 to 77.5 years for those born in 2022.

Healthspan, however, has consistently lagged behind, largely due to high rates of age-associated chronic conditions including cancer, dementia, and heart disease. Many Americans also don’t sleep enough, exercise enough, or eat enough nutritious food, all of which can detract from long-term well-being, Peterson adds. But that’s not to say this is a uniquely American problem. Global lifespan has risen to 73.4 years, while healthy lifespan lags behind at 63.7 years, according to the WHO’s 2019 estimates.

“Yes, we live longer,” says Dr. Andre Terzic, a regenerative medicine specialist at the Mayo Clinic. “But there is a price to pay, and that price is we may not necessarily live healthier, longer.”

Closing the gap between lifespan and healthspan is an appealing—though lofty—goal for some researchers, policymakers, and entrepreneurs. The United Nations deemed 2021-2030 “the decade of healthy ageing,” and the American Heart Association is striving to extend U.S. healthy life expectancy by at least two years over the same decade. Meanwhile, startups are peddling consumer-targeted solutions, like DNA tests that spit out personalized recommendations around how to eat and exercise for extended health, even though some experts caution they’re getting out ahead of the science. And some companies are developing therapies meant to counter the effects of aging, with the goal of lengthening healthspan.

In a 2021 paper, Terzic and his colleagues laid out promising paths for closing the healthspan gap, ranging from global tobacco cessation to developing drugs that kill off damaged cells that accumulate during the aging process. Other researchers are looking for ways to turn back the aging clock through gene therapy and restoring the protective caps on the end of DNA strands, among other approaches.

Terzic points to cancer immunotherapy treatments and genetic testing for certain chronic conditions as evidence that medicine is moving in the right direction. Peterson says newer diabetes drugs like Ozempic and Mounjaro could move the needle, too. There’s also some evidence that drugs including metformin (an older type 2 diabetes treatment) and rapamycin (an immunosuppressant) may extend healthy life—leading some biohackers to take them off-label for that purpose, even before the science is settled.

And, earlier this month, the U.S. Food and Drug Administration (FDA) said a drug that may extend canine lifespans has a “reasonable expectation of effectiveness,” a step toward granting it conditional approval. That’s a big deal not just for dogs, Peterson says, but also for humans, since it signals the FDA is willing to consider drugs that target aging itself, rather than diseases that often accompany it.

Emanuel agrees that expanding healthspan is the right goal; he just has a different take on what that should look like. Rather than developing new aging-reversal drugs that, at least at first, would likely cater toward wealthy people who can pay for them, Emanuel feels the medical system should tackle long-standing health problems including hypertension, diabetes, and maternal and infant mortality—all of which are treatable or preventable, and all of which are most prevalent among the underserved populations that are also most likely to die and develop diseases even younger than the national average. Black and American Indian/Alaska Native people in the U.S. have life expectancies of 72.8 and 67.9 years, respectively, according to the new 2022 data.

So much of life-long health, Emanuel says, also comes down to behaviors like eating a nutritious diet and getting enough sleep, exercise, and social support—things that are simple on their faces, but in practice far more achievable for people with leisure time and money. As he sees it, promoting and enabling those habits for everyone, and making better use of medical treatments that are already available, is a more urgent priority than chasing the “pipe dream” of a future in which aging is optional.