I actually kinda believe this since she did mention someone who had broken her heart, and in her tv show she was trying to get him jealous by going to the iHeart Radio festival with a random guy. And this guys identity was always kept a secret. I truly believe this is a big factor, along with the Dr. luke drama, and just many other things she has been through. An eating disorder is not gonna happen because of 1 situation;instead of many situations that built up into a bigger one.