Why do they have to be fat?

TV show's such as Family Guy, The Simpsons, and King of Queens (to name a few) are just a couple of titles to include in the list of shows that have a bigger, usually dumber male as the main role. Why is this? Watching these series it is always interesting to picture a more sculpted male character that has a stable high paying job and gets what done what needs to be done. Usually the female characters (mainly the wives) are those who have their heads on straight about life and the ones making adult decisions. This feeling of men being dumber is also branched out to the main characters friends, usually being a slight variation of the main character but still considered not as smart or headstrong as their wives.
    Family Guy took this idea to a new level when in one episode they transformed Peter into what would appear to be a perfect male figure, with a sculpted figure and while the dumbness remained even just the appearance of Peter Griffin changed the dynamics of the show. People still talk about how that episode is unpleasant or just weird simply because Peter isn't fat. It is because for some reason it just isn't as funny some people say. The awkward and hilarious encounters these characters have simply wouldn't be as funny if the person isn't overweight, it draws a certain type of comedy from the created person and removing that element changes the show drastically.
    As discussed in class, the thought of all these shows based around this type of male character were to be replaced with good looking males the shows wouldn't be as funny. The comedy aspect around an overweight person doing these hilarious things for some reason draws more laughs out of a viewer than a normal male would. So is this bad?
     Are these shows teaching us that overweight people are more funny simply because they are overweight? I don't believe they are; but having thought recently more about this topic the thought of why all these shows center around certain types of people make me question, why do the lovable yet dumb male characters have to be fat?