It doesn't have to be an organized, deliberate conspiracy, as when Leftists pretend there's no vote fraud or denying that many of them are paid agents of Soros or that Clinton isn't horribly ill. The homosexuals pursue their burning lusts and pervert the ways of the Lord. Always have, always will. These in particular are in very high places of worldwide influence, and sewage always flows downhill. The effect has been gradual and cumulative, but definite.
Even in the 1920s the general standard of attractive women (at least in the U.S.) was noticeably meatier than what you'll see on the covers at the checkout. Not fat, particularly, but simply with more body mass.
That began to change in the 1930s. I've seen some hypothesize that the homosexual influence in the movie industry began to have an effect even back then (casting directors, producers, fashion stylists, etc). However it took place, it is beyond dispute that the perception of "the ideal woman" in media has gradually become more physically boylike to the point of androgyny. Lots of models now resemble adolescent boys with breasts, which is exactly why you now we're beginning to have actual trannies in drag on magazine covers. The message is: we're all interchangeable and so are our orifices.
I for one cannot believe that was a natural shift that just happened...women were influenced by increasingly thinner celebrities of various kinds. The tastes and perceptions didn't just change, they were changed.
