I think weight is a problem in a lot societies, merely because of the way the human body is made. One of the biggest goals of the human body, if not the biggest, is to fight starvation. If you starve you cannot live long enough to breed, and thus fighting starvation is very important. And the fatter you are, the farther you are from starvation in your body's eye.

One thing I have also noticed is that many people who talk about weight problems do not have them themselves. Some people get to eat and eat and sit around and not exercise and do not gain any weight. In contrast, people like me struggle with our weight and have to enact a much higher level of self-restraint then our skinny counter-parts. It's not at all easy in any way, and it makes me angry when skinny people talk about it like it's nothing.