It's not just the 'media', by which I believe you all mean tv, movies, magazines etc. The media, appropriately, is simply the vehicle (medium, see?) for the message:
"You are not good enough as you are, so you must buy things to make yourself better."
This is the root of it. Creating this kind of psychosis in young people, as young as you can get them, sells things, it creats a market. Not only for diet foods, but for junk foods as well. They push the yummy, empty stuff on you, and then make you feel guilty about eating it. Then you buy stuff to make yourself feel better, whether it's a pint of B&J or an excersize video.
But even the doctors are in on it. Believe it! They work for an industry and they have become as brainwashed as the rest of us. Who cleans up when unhealthy people need treatment?