Princeton , New Jersey ( CNN ) -- New Jersey Gov . Chris Christie made headlines last week when one of his aides admitted that he had surgery to lose weight . Christie said that the surgery had nothing to do with politics and everything to do with his health and his family . Christie said : `` It 's not a career issue for me . It is a long-term health issue for me and that 's the basis on which I made this decision . It 's not about anything other than that . '' It is impossible to know whether we should take Christie at face value . Given that there has been ongoing speculation about his presidential aspirations for 2016 , often coupled with discussions of his struggle with weight , it is certainly not unreasonable to wonder whether these are related . Why do Americans care about the weight of a candidate and why is appearance an issue in presidential elections ? There is very little chance that the issue will go away . Certainly , old-fashioned bias has something to do with this concern . The willingness to ridicule obesity and make fun of appearances based on weight remains more acceptable than other kinds of biased comments that are no longer tolerated . One study by Yale University recently showed that male jurors were biased against heavy women , and more likely to find them guilty than leaner women . Some have called obesity the last acceptable bias in American life . Opinion : Congrats Gov . Christie - You saved your life . We are also in a political era when politicians are more in the public eye than ever before . Like it or not , appearance matters . When William Howard Taft -- weighing in at over 300 pounds -- was president , most Americans rarely saw him , though jokes about his weight still circulated . But it was still a very different world . In the early 20th century , there was no television or Internet broadcasting constant footage of the president in action . Other than the occasional still image in the newspaper , or the footage in the newsreels before movies until the 1940s , politics was still a medium of words and print . Since the emergence of television , however , we live in a visual political culture where appearances have become much more important . We vote based on what we see , or at least that is part of the calculation . It has become more important for presidents to convey the charisma of a John F. Kennedy and harder for those who are not as easy on the eye . Shallow visual preferences are not the only dynamic at work , however . The last half century has witnessed massive improvements in personal health . Americans are living longer and living better as a result of great advances in our understanding of nutrition and physical care . It is no longer uncommon for Americans to use a gym on a regular basis and to be much more cautious about what they eat . We expect politicians to live by the same standards . Indeed , we want our leaders to set examples for the rest of the nation . Christie is certainly not the only candidate to face these kinds of questions . When Bill Clinton ran for the presidency in 1992 , the media covered his tendency to eat junk food on the campaign trail and his weight gains were treated as problematic . After Clinton gained 30 pounds during the Democratic primaries , Hillary Clinton noted , `` The good news is , my husband loves to eat and enjoys it . The bad news is , he loves to eat , even when things are not always right for him . '' Another reason that weight and other physical health concerns have become more important is that the job of the presidency has become much more demanding . As the role of the federal government has expanded at home and the presence of the United States overseas has intensified , there is much more for a president to handle on a daily basis . The massive size of the executive branch and intense 24-hour news cycle makes the presidency a physically brutal job . We often watch as presidents enter the White House looking young and spry , then exit with gray hair , tired and visibly worn down . As with many other high-powered jobs , physical health is important to the ability of a person to handle these kinds of tasks , so it is logical that these considerations enter into the conversation . All of this is to say that there are many reasons why voters and reporters will talk about Christie 's weight , and why Christie 's weight could become a major issue if he runs for president in 2016 . It 's important to note that there is some social science evidence that in certain cases voters may not be swayed by weight . In fact , according to one study , voters in certain cases can prefer obese to non-obese candidates . The studies showing this finding are still limited and , from the evidence of the presidential races of the past century , the signs still point to voters preferring candidates who are leaner . There is clearly a huge risk in making our decisions about leaders based on appearances , which really do tell us little about what a person would do when faced with the big challenges of the day . Regardless , the conversation is unlikely to subside , given the times in which we live . The opinions expressed in this commentary are solely those of Julian Zelizer .
Chris Christie , a potential presidential candidate , had weight - loss surgery . Julian Lewis says candidates should n't be judged on appearances . But Americans will inevitably take weight and appearance into consideration , he says . Zelizer : Job of presidency is constantly in public view , and extremely demanding .