A lot of "people" already believe it is ok to be fat, at least that is what they say and try to force upon others.  It is very possible and likely that inside they know damn well it is not ok to be fat.  I bet 100% of all the real womyn tumblr types who preach the "obese womyn are the MOST beautiful/desirable"  message the loudest would give/do anything (except any work) to have human shaped bodies.  Like if they were granted one wish it would be to magically have a human body (with the ability to eat as much as possible with no effects on said body).    Being fat will never ever be attractive.  It would take some very serious brainwashing.