Well, yes and no to a lot of things here- between you guys, most of the major stuff has been at least alluded to.
* Yes, stereotypes do exist and are still prevalent today- it's just that they're now more the subject of debate in this day and age. Historically speaking, it used to be desirable to have a bit (or a lot) extra, because it was a sign that one was prosperous enough not to have to worry about putting food on the table. Also, life expectancy was lower then so things like cardiovascular disease were hardly as much of an issue as they are today. It was only when some societies became more prosperous such that food was no longer such a concern, that the tides began to change. Now it carries a moral weight which is often unjustified.
* The bottom line is this: Weight gain/loss is dictated solely by how much energy you put in versus how much you put out (not accounting for water retention).
* However, this is hardly as simple as it sounds! There are lots of factors influencing how much one puts in, and how much one puts out. It comes down to genetics, metabolism, your tendencies (are you a fidgeter? Are you naturally hyperactive?)
* This is not to say that everybody is the victim of the vicissitudes of biological fate. To varying degrees (this is important), people can generally manage their states, both by adapting to it and changing it- sometimes it changes by themselves (commonly kids somehow magically lose the 'puppy fat' when they hit puberty or adulthood- this happened to me). Unless, for example, you have something like Prader-Willis syndrome, in which you have no control over your appetite because one of the main chemicals that regulates it no longer works.
* Still, in general it doesn't hurt to be fit, no matter your weight status.
