I have often heard that only recently slim women were considered as more attractive in western society. It is referenced a few time in this Slashdot thread: Government Should Ban Skinny Models To Curb Anorexia, Say Researchers. There is also this webpage by the some municipality that wants to show that the new trend started in the 1900's while in the 1890's:
Actress Lillian Russell at 200 lbs. or 91 kg. is the most celebrated beauty of the time.
They of course don't have any reliable source and I don't consider 90kg as 'that' fat (she may be 6'6"). So anyway, is there any evidence that before the 1900's, or for some specific time, fat was considered as the norm of beauty?