Just wanted to add my two cents
Firstly- I'm sorry you haven't been taken seriously by professionals- it takes guts to go out there and speak to someone.. just then to be dismissed.
I wonder though that this isn't necessarily due to being overweght, but more a failing of the medical profession to recognize the serious-ness of ED's? I say this as I have been to many GP's over the years and have never been given any support or have been taken very seriously. I am underweight (not by much) and have been back and forth between average weight for years.. Yet doctors have always weighed me and said I am 'okay', therefore not doing anything.. despite my being totally honest about the severity of my behaviours.