When you picture an American president deciding to contribute to a magazine, chances are Sports Illustrated isn't the first publication that comes to mind.

Granted, it wasn't the swimsuit issue. But in 1962, an article entitled "The Vigor We Need" by John F. Kennedy appeared in the July 16 issue of the magazine, expressing the president's concern about deteriorating levels of American fitness.

Today obesity may be a household term, but 46 years ago problems associated with the growing population of overweight Americans were just beginning to enter the national consciousness. In an effort to address them, JFK reorganized the Council on Youth fitness to instigate a series of student exercise programs in several states, but his effort to combat the technological and cultural shifts that made the American lifestyle more sedentary was too little, too late — as is evident in this animated map of U.S. obesity trends from 1985-2004.

As for Kennedy's collaboration with Sports Illustrated, it was not his only — or the only in the history of the U.S. presidency. JFK is joined by Gerald Ford, Ronald Reagan and Bill Clinton to round out a rather exclusive little group — American presidents who have graced the cover of SI.