I saw this yeaterday when i was watching This Morning and i do think its quite common. I think we have all been in denial at some point!
I know a friend of a friend who is a good size 18 and she buys size 12/14 clothes and squeezes herself into them and sometimes wears obscenely small skirts and dresses but she is not bothered. We have been out and people have been looking at her when she is wearing a stupidly small skirt with a rather ample pair of legs and she actually says to us ''Have you seen that lad looking at me, he must want to chat me up'' - its madness!
I don't think it's a real 'illness'. Obesity is an illness as is binge eating etc . She was clearly in denial about her weight and reasons behind it, which is often part of the illness of obesity, but creating a new 'illness' to sell a book is just crap!
I think it is important to find some way to draw a line under your weight problem and maybe take on a different mindset. Fatorexia is not encouraging people to go on a diet just to accept the way they are and change maybe one thing at a time. Sometimes diets are just expected to fail as we try so many times and they don't work.