if anorexics don't eat anything and become really thin, then why do bulimics "maintain" body weight instead of end up the same as anorexicx when they purge out everything they've just eaten? doesn't purging pretty much take out all the calories that they once consumed.

I don't believe that bulimics throw up every time they eat, only sometimes.

As a guess I would say it has a lot to do with absorption. Purgers don't always purge immediately so some calories are absorbed. I think they also tend to binge on sugars which are more readily absorbed as calories and affect blood sugar much more quickly.

 

Some bulimics use laxatives instead of purging. This would cause them to retain more calories as well.

 

 

 

[MOD]I moved this thread to General Medicine since your OP was targeted towards a more physiological question. If the replies tend more towards the psychological ramifications of eating disorders, I'll move it back. [/MOD]

if anorexics don't eat anything and become really thin, then why do bulimics "maintain" body weight instead of end up the same as anorexicx when they purge out everything they've just eaten? doesn't purging pretty much take out all the calories that they once consumed.

People with bulimia don't always purge. They go through 'binge - purge' cycles. On a binge they can consume truly amazing amounts of food before they purge. The fact that most bulimics maintain a more or less normal BMI is a part of the risk. They are very hard to spot but chronic purging leaches electrolytes from the system and during severe binge-purge episodes they are at high risk of sudden death. The heart fails due to low potassium.