This paper argues that there is a relationship between understandings of anorexia nervosa (AN) and how the ethical issues associated with involuntary treatment for AN are identified, framed, and addressed. By positioning AN as a construct/discourse (hereinafter “AN: the diagnosis”) several ethical issues are revealed. Firstly, “AN: the diagnosis” influences how the autonomy and competence of persons diagnosed with AN are understood by decision-makers in the treatment environment. Secondly, “AN: the diagnosis” impacts on how treatment and treatment efficacy are defined (...) and the ethical justifiability of paternalism. Thirdly, “AN: the diagnosis” can limit the opportunity for persons with AN to construct an identity that casts them as a competent person. “AN: the diagnosis” can thus inherently affirm professional knowledge and values. Postmodern professional ethics can support professionals in managing these issues by highlighting the importance of taking responsibility for professional knowledge, values, and power and embracing moral uncertainty. (shrink)