Society's standards are created from us. There wasn't a meeting of The PatriarchyTM in which it was arbitrarily decided that hot/healthy/happy = thin.  People who talk about that kind of thing seem to almost never have any real understanding of the history of various fashion trends. It's pretty bad when someone is trying to argue from an expert position and it's clear that they couldn't even be assed to spend a few minutes on wikipedia looking up the history of whatever trend they're discussing.