Complex sentence: Perfectionism is a life enduring trait in the biographies of anorexics; it is felt before the onset of the eating disorder, generally in childhood; during the illness, and also, after remission.
Split into simpler sentences: Perfectionism is a life enduring trait in the biographies of anorexics. It is felt before the onset of the eating disorder, generally in childhood, during the illness, and also, after remission.