My sister struggled with anorexia before tumblr and Instragram. All of the same elements appear to present, with the exception of the amplifying quality of social media.
This is a standard model/actor weight- I have seen pages listing the heights and weights of lingere models (VS, et. al), and while they were slightly taller, they were in the same range- 5’9, 119 lbs, and so on.
As long this narrow ideal of sexy and desirable dominates the imagery produced by the fashion and film industry, these groups aren’t going anywhere.