We first discuss current diagnostic issues concerning the classification of anorexia nervosa (AN) by reference to the proposed criteria of the fifth version of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). We strongly welcome the changes in the latest revision of DSM-5 (update April 2012), which in our opinion partially solve the previously delineated classification problems. Nevertheless, we still miss a standard or reference(s) for the weight criterion including the delineation between a healthy and unhealthy underweight, a better operationalization of observable behaviors including symptoms of disordered eating, readily accessible cognitions and a better allowance for cross-cultural aspects in the proposed DSM-5 classification of AN. In the second part, we review the treatment recommendations of the NICE guidelines for AN, which overall are characterized by a lack of evidence. Nevertheless, NICE recommended an outpatient treatment setting based on one randomized controlled trial with many methodological limitations. A review of the current literature shows that (a) the optimal treatment setting (inpatient vs. outpatient treatment) still is a subject of debate, and (b) the evaluation of treatment costs in AN plays an important role within this discussion. In contrast to the German Guidelines for the Treatment of Eating Disorders, NICE does not offer any specific criteria for the clinician with regard to determining the adequate treatment setting.