Good theory - the fashion of this era is considered 'prim' and 'controlled' in modern-think so fatties are trying to blow our expectations that they are greedy and desperate whores by wearing it? ( hint: it's NOT WORKING). My working theory is because many beautiful women of the era wore a then-size 14/16, even though they were a size 00-6 in today's money, fats can convince themselves that they look just like them, because they have the same size on the tag.