Full credit to Wilson6 for a concise and accurate summation.
I will just add that I've seen 'normal' people develop eating disorders as a RESULT of adhering to a strict BB diet and getting down to unhealthy levels of leanness. In these cases I have no trouble saying that the lifestyle caused the disorder rather than the other way around. But I think this is biochemical in origin (disturbances in leptin, neurotransmitters, gonadol steroids etc...) and it usually resolves itself with time.
Also, a certain level of compulsiveness may be what separates top notch BBs from the rest (genetics and drugs aside). It does take a lot of discipline to get to the top and stay at the top in any profession, and mild obsession and compulsion may be helpful. Like circusgirl pointed out, it's only a disease when it interferes with the rest of your life. How many of you have lost friends and partners because of your unwillingness to compromise on your BB lifestyle??? How many of you have imported illegal substances, or taken drugs that you know carry a significant health risk just to lose fat when you were not even overweight to begin with?? It's not just about eating disorders-that's just the tip of the iceberg. It's easy to be smug and say "I don't have a problem, it's the rest of the obese world that has the problem". But a quick tour of the diet discussion board should convince you that there's a lot of BBs out there that have serious issues with food, drink and nutrition which I could only describe as 'obsessive'.