Re: Why assume that?

Taking care about the body improves both physical and emotional health.

Yes, but this has nothing to do with beauty. Accepting of what one is born with and maintaining your body to be fit and healthy is fine and will produce better results than any amount of fussing over appearance. True friends love you for who you are, not for the appearance of who you would like to project. Seems common sense to me.

Lack of care leads to physical "lifestyle diseases", and has a negative effect on emotions.

See above - nothing to do with beauty and appearance.

Why do you want that?

Why wouldn't I want to see healthy individuals - inside and out - and this doesn't come from an obsession with how one looks. As I said, if it starts very young then it probably will have a negative impact throughout their lives. There are much more important things to devote one's time to than physical appearance.