I have always found these to be fascinating topics. I majored in psychology with a minor (and so many of my electives) in history, including taking a Sex in History class which highlighted other ways in which both illness and socioeconimic changes influenced standards of beauty and fashion. I mean, the whole idea of the artificial beauty mark came about from attempts to cover up and beautify pock marks left by illness and acne scars.
Besides the examples @Sashira mentioned…there is also evidence to support that the rise in popularity of ridiculously large and decorative codpieces came about with a widespread outbreak of an aggressive strain of syphilis that would have necessitated the use of thick bandages around the…err…afflicted appendages. Dresses also became more elaborate and used more fabric among the rich in times when having those materials were in higher demand due to wars, trade issues, or overall economic depression in order to show off how wealthy they were through being able to “waste” that much fabric of frivolous designs.
It is also my understanding that this is true of “fashionable weight” (I know, eyeroll, but from a purely sociological standpoint). Pressure put upon women, by the general public or industry, can fluctuate with the economy much in the way having paler/tan skin does. In other words, in times of hardship or in the recovery periods after a war/drought, being curvier and heavier is seen as a sign of affluence and fertility and is therefore more desirable. This can be tracked through photographs and, earlier on, trending in drawings and paintings, as cross referenced with majors events of the era in which they were made. Of course, there are also times where power plays on the gender spectrum, the most information about which we historically have within largely patriarchal societies, have also played a part, such as the “boyish” trends of having a more linear silhouette and short hair among flappers, or the way high heels originated among the French male aristocracy and later became considered almost entirely a woman’s shoe.
Anyway! Sorry, maybe that’s more of a response than you anticipated with the thread, I just think this topic is SO INTERESTING! I love talking about and researching this stuff. My inner history geek comes out every time. Consequently, I am also the worst person to watch historical dramas with if their fashions are not period accurate.