Like someone has said already that society looks at fat people and make judgements about them i.e. lazy, sloppy, lack of willpower. In some cases that is very true others not.....but, here is another spin on things.
A fat person wear his weakness for the world to see so we can make our snap judgements about them, were as the pedofile, liar, theif, rapist, murderers don't. We can't look at those people and see the bad horrible things that lie within them. Things society deams as bad, things that in fact are truely reprehensible.
I don't in any way mean to say that fat people are anything like muderers, rapists and such.....! Just using that as an example!