Every culture shapes the bodies of its people according to its own values. Our culture is not different.
Since we consider the body more as an instrument of expression (think of a paintbrush) than as a carrier of expression (think of a painted canvas), we don’t treat it like an artwork to be admired and preserved, but like a tool to be used and disposed.
A Human is supposed to act as a subject: your focus should be on what you do, not on how you look. Treating your body as an object is almost a taboo: it is perceived as a display of servility, vanity, trickery and pushiness.
The above list is not exhaustive, needs many explanations and there are some exceptions to it, but it is useful to get an idea of how a Human looks like.
Our main influence on this subject is this extract from Plato’s Republic: “Among all well-governed people each citizen has an appointed function that he must perform, and no one can afford to spend his whole life being ill and being treated by doctors”.
We’ve just changed the last part: “[…] and no one can afford to spend his whole life putting makeup on and being on a diet”.
Il Vento d'Oriente 