President Obama, in 2009 and 2015, has amassed many grey hairs during his seven years in the White House. (Left: REUTERS/Larry Downing) (Right: Jim Watson/AFP/Getty Images)

Donald Trump's long-time personal physician wrote in a letter released Monday that Trump would be the "healthiest individual ever elected to the presidency" if he wins the election. But a new study suggests that if he wins, he'll also lose 2.7 years of his life, to be precise.

For years, world leaders have appeared to age rapidly right before our eyes, their faces pinched by the stress of each passing year, their hair grayer and perhaps a little thinner with each passing month. One theory goes that for every day in office, a president ages two days. But are our eyes deceiving us? In 2011, a study of U.S. presidents found that leading the United States was no worse for a person's lifespan than merely being a citizen in it.

However, the new study, published in the British Medical Journal on Monday, reopens the question of whether winning an election is a health hazard. The authors compared the leaders of 17 countries with the would-be presidents and prime ministers who lost the elections. The idea was simple: winners and losers are more similar to one another than they are to the average resident, so lifespan differences could reveal the real health toll of leading a country. The researchers calculated that the price of winning an election is nearly three years of life.

Leading a country "probably is medically ill-advised, in the sense that there's certainly a plausible risk of higher mortality if you're elected to lead," said Anupam Jena, an associate professor of health-care policy at Harvard Medical School who oversaw the study. "But we make all sorts of trade-offs in our lives because it gives us joy or it is for a greater social good."

Margaret Thatcher smiles at her first conference as Conservative prime minister in 1979 -- and 10 years later. (Left: UPI) (Right: EPA/Wolfgang Eilmes)

Are presidents really aging more quickly? 

The researchers gathered data from international elections going as far back as 1722, when Sir William Wyndham, 3rd baronet, lost a United Kingdom parliamentary election to Robert Walpole. After adjusting for the life expectancy of people during different eras, the researchers were able to discern the overall pattern that led them to conclude world leaders are aging faster than the wannabes, although they don't know exactly why.

"This intriguing study is actually broadly consistent with lab experiments in which, for example, sleep deprivation has been shown to be detrimental to longevity in rats and insects.  The underlying mechanisms are largely unknown," Andrew Oswald, a professor of economics at the University of Warwick wrote in an e-mail.

Not so fast, said S. Jay Olshansky, a professor of public health at the University of Illinois at Chicago, who did the original study showing that presidents weren't aging faster than the rest of us. Olshansky said the new study did show an interesting fact: Elected leaders were more likely to die at an earlier age than losers, overall. But the study couldn't address whether they were aging faster than losers, he said, because it didn't exclude leaders who died of accidents, assassination or other causes not related to aging.

Olshanksy said that stress can bring on rapid graying of hair or even wrinkles, but that the main thing happening to presidents is that they are aging in public view as they are photographed every day and scrutinized for their appearance on good and bad days.

"These presidents and political leaders are just experiencing the same aging the rest of us experience -- except we see it," Olshansky said. Looking older doesn't mean dying younger, he added.

His takeaway from the study is that there's still no evidence that presidents and prime ministers are actually aging faster than their opponents and, moreover, these people -- at the very top of the socioeconomic ladder -- aren't living truncated lives compared to the rest of us. Far from it. The first 10 presidents, he pointed out, had an average life expectancy that hovered around 80 years old, at a time when, on average, citizens died around age 40. If anyone needs anecdotal evidence that being president may confer some health advantages, one only need to look to former president Jimmy Carter, 91, whose cancer diagnosis this summer was a national news event that was followed by top-notch care that means his cancer has now vanished.

"I say you don’t have anything to fear from this study; you’re part of the one-tenth of the top one percent of the wealthiest, most highly- educated people who have access to the best health care," Olshansky said. "You’ll do just fine."

Vladimir Putin as acting president in 2000 and as prime minister in 2008. (Left: Ivan Sekretarev/AP) (Right: Alexei Druzhinin/AP)

The health effects of winning

The study is the latest addition to an unusual literature analyzing the life expectancy of people who have won various honors, including Oscars, Hall of Fame induction and Nobel Prizes.

Oswald, of the University of Warwick, said the interest in studying winners and runners-up stems from a very old question about how success affects people's lives. Because researchers can't ethically design and conduct experiments in which people are rewarded (or not) over a lifespan, prizes can offer a convenient way to probe the effects of status on health.

Oswald's work, for example, has included an examination of Nobel Prize winners' longevity, finding that winning the prize confers an extra year or two of life when compared with those who are simply nominated. Studies of winners of pretty much everything else -- Oscars, Emmys, baseball Hall of Fame induction -- have shown mixed results.

“Our findings and results of similar studies fail to show consistent advantages for winners. The association between winning and longevity is sometimes positive, sometimes negative, and sometimes nonexistent,” researchers wrote in a study published in American Sociological Review in 2013.

All that suggests that this approach may be a tricky way to examine the longevity benefits, or not, of status -- which may explain why this paper ended up in BMJ's Christmas issue, which publishes rigorous research results with a lighthearted bent.

A call to the office of Harold Bornstein, the New York physician who wrote in a letter Monday that Trump's lab test results were "astonishingly excellent" was referred to the campaign. The campaign did not immediately reply to the question of whether Trump had weighed the mortality risk in his bid for president.