HI --wasn't sure where to post this so ..this seemed as good a spot as any. i have read about the genetic predisposition for developing Anorexia...that initial weight loss triggers neurotransmitters to start misfiring etc. BUT im wondering about people with Bulimia...what's the deal with them...the above theory doesn't explain why a normal weight individual suddenly starts binging and purging...im curious...what causes that?

Bulimics rarely start by bingeing and purging. Almost 2/3 of all anorexics become bulimic within 8 years of the onset of the restrictive eating disorder. It is rare a bulimic begins with bingeing. A bulimic must first create an energy deficit of some kind to bring on a so-called 'binge', which is just reactive eating (eating to restore the energy deficit created by the diet).

Often when you interview bulimics they have to be guided to identify the actual origins of their condition and you will almost invariably find it began with a diet. Also, there was weight loss but it may never have gotten to a point of being identified as clinically underweight. If you start at BMI 24 and starve to BMI 20 you are anorexic, but it will only be the woman who starts at BMI 21 and goes to BMI 17 who would be clinically identified as anorexic.

Many bulimics will say that they learnt how to purge from friends and it meant they could eat whatever they want and still stay thin, then it got out of hand. That's not the entire story. Everyone of them begins in a culture of dieting. All their friends first and foremost try to restrict intake to stay thin (ages 11-13 most commonly). The hunger invariably becomes unbearable and when they finally succumb they apply restriction through purging to try to alleviate the anxiety that consumption of food has generated.

Bulimia is profoundly misunderstood in the psychiatric, psychological and medical communities because the focus for the patient is on the anxiety of bingeing and no one thought to consider "Why is there anxiety over 'bingeing'?"

In fact there is anxiety over food intake -- the same anxiety over food intake experienced by anorexics, orthorexics and those with anorexia athletica as well. Bulimics however end up with bodies that fight back. They are just as intent on starving as an anorexic, but their bodies insist on rectifying the energy deficit. The purging develops in response to the extreme anxiety that reactive eating causes. The patient then returns to trying to 'eat normally' (which means restrict calorie intake to what she considers acceptable) and the cycle inevitably repeats.

Bulimia is stabilized in the same way as anorexia: adequate food intake to restore a stable, optimal homeodynamic system. They have to eat recovery amounts of food just like everyone else on the same spectrum. It may involve a temporary overshoot in their optimal weight as the metabolism adjusts back to normal, but just like everyone else they only gain to their optimal weight set point (sometimes 10% above that but it returns to the optimal point in the year following recovery -- we presume this happens for some in recovery (not just bulimics) to refine the fat mass to fat-free mass ratio to be healthy).

2/3 of all patients on the restrictive eating disorder spectrum (irrespective of the symptoms they have -- starving, purging, reactively eating, obsessively exercising etc.) are not clinically underweight nor have they ever been.

It's all about restriction. The enemy is restriction.