I mean when I was a kid nobody did it, when I was in highschool all the classes had at least 3 girls doing it and nowadays nobody does it anymore at those rates (I have 2 friends who now teach at the highschool we went to). Thats what it means to me. And there's plenty of papers documenting this rise and fall which happened to line up with my generation. Regarding papers I read some when this topic came up in a podcast and was convinced and there were a lot of results for a query like "social contagion bulimia papers".