US presidents like Barack Obama, who seemed so youthful just a few years ago, appear to age right before our very eyes during their terms in office. This simple observance led Jay Olshansky, PhD, a professor of public health at the University of Illinois–Chicago, to question whether the stress of being Commander-in-Chief can really take years off someone’s life.

Dr. Olshansky collected the birth, death and inauguration dates of every American president who’s still living and those who died of natural causes. Then, based on their time in office, he estimated their projected lifespans under a theory posited by Dr. Michael Roizen, who in August said presidents effectively age twice as fast while in office.

The results? Olshansky found that not only have two-thirds of presidents lived longer than their projected lifespans, they’ve also exceeded the average lifespan of men overall. In fact, our first eight presidents lived to be an average of 80, more than twice a man’s life expectancy at the time.

Olshansky said this is partially because wealth, access to healthcare and education are all closely linked to longer lifespans. Just so you know, presidents have all three resources in abundance.

So why do they look so much older when they leave office? Well, for one thing, they are older. They also usually enter office in their mid-50s, a time when the external signs of aging tend to become more pronounced in men.

As for the gray hair, Olshansky says, “There is good, strong literature to suggest that stress can lead to accelerated graying of hair… but at least with regard to the presidents, [stress] doesn’t appear to be making them die sooner. No one dies from gray hair and wrinkles.”

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