Came here to say this. The term "anorexia" on its own is just "lack of appetite". We used to use it to describe sick cats and dogs who were refusing to eat for extended periods of time. So you don't need to be thin (or even human) to be anorexic. "Anorexia nervosa" is the eating disorder. The DSM V lists a BMI below 18.5 as one of the symptoms - therefore you can't be fat and have anorexia nervosa. I wouldn't understand fats to understand the difference though. They just want to be able to say they have anorexia (nervosa) because it's another trophy for them in the Oppression Olympics