(MEDIA GENERAL) — As Barack Obama wraps up his second term as president, people are looking back and reflecting on his lega– and who is the strapping, young man taking the oath of office?

When Obama took office he was a fresh 47-year-old eager to bring reform to Washington. As he steps down from the presidency Jan. 20, he is a graying 55-year-old that has taken his fair share of punches during his two terms.

Due to the high-stress nature of the position, the White House ages presidents faster than normal, according to several scientific studies.

Dr. Michael Irwin of the UCLA Neuropsychiatric Institute agrees with studies, telling the Daily Mail, “it is unequivocal that significant life stress perceived by a person does accelerate aging.”

However, that does not mean presidents necessarily will die young. A 2011 study published in the Journal of the American Medical Association shows that though presidents typically exhibit signs of aging during office, they often outlive standard life expectancy.

Studies agree the job takes its toll on them all. Take a look at this gallery of past presidents and see for yourself.