i had a crazy thought, and it's not what i think is truth or anything like that but here's a hypothesis.

man has always had a need for food for energy, and he had to work for it. when he obtained it, he used it.
now it's right there all the time. there's so much that our natural balance is off and good old adaptation is taking place. our bodies are starting to say "food isn't too important." this would explain the growing adoration for thin bodies in regular people ( a subconcious value for a righted "wrong" ) and the eating disorders in those that are actually caught in nature's attempt to balance this b0rked equation.

i just got way too analytical.