I think America has had several FAT presidents. Like president Taft, Teddy Roosevelt, McKinley etc..etc..
However, they were elected in a different time. Now, US presidents are on TV almost every day and their picture is taken every day as well so it is more visual. It was not until the very first televised event (Nixon vs Kennedy) where people got the first glimpse of a debate on TV. Kennedy, younger and better looking than a heavily sweating Nixon won).
The fat presidents were elected before the media followed the present day presidents.
Chris Christie knows he is fat and does not deny it nor does he make apologies for it. But generally, there is a lot of discrimination against overweight people in America. Though he was elected governor, morbidly obese people suffer more unemployment, lower wages etc. And people mock them all the time. "Stuff your face, fatty, etc..etc..
On one hand, those who discriminate against fat people would take Christie's weight against him. Like saying, he doesn't care about his physical appearance, can't control his weight- how can he run the country? Then there is the question of how healthy he will be? Dick Chaney had a lot of problems with his heart- to the point that people were asking, if anything happens to him and the president- what would happen? Then there are the stereotypes. A thin person can job up the stairs and feel fine, a morbidly fat person has more girth and may end up sweating up the stairs. There is the "fat people are more lethargic" stereotype and people don't want to think of their president as a "lethargic over eater". I am not saying Christie is one but I am talking about the stereotypes.
Also, there is the question of "world appearance". How many world rulers are morbidly obese? Other than a bunch of fat arab monarchs, I can't think of too many fat world leaders. Putin is thin, David Cameron is thin, Julia Gillard is thin, Netanyahu, Hollander etc.. not fat. German Chancellor Merkel is a rounded lady but not morbidly obese. But the list goes on.
But we will send a morbidly obese peer to these world leaders? What image does that give America? The world laughs at us because they know we are the FATTEST nation. And when we send out fat president to G8 Summits and on world leader banquets, we will be a mockery. The fat president to the fat Americans.
I am not saying that a morbidly obese person cannot be president- but if Christie is stubborn to say that he is healthy and there is nothing wrong with his weight...then that is something to consider because that is just pride and arrogance.