In connection with the current knowledge of interdisciplinary results of research, we discuss clinical syndrome transitions of psychotic and non-psychotic quality in the course of anorexia nervosa. According to its internal and external conditions, anorexia nervosa can in principle occur in any person and in any phase of life during a critical trial situation as an ontologically given possibility of specific psychosomatic reaction. In the course of a mainly neurobiologically determined protopathic change of psychologically initiated cross-sectional psychopathology, very heterogenous secondary syndromes (impulsive, phobic, obsessive-compulsive, addictive, autoaggressive, depressive and schizophreniform) may facultatively become manifest. The similarity of such anorexia nervosa metamorphoses with classical nosological disease entities is likely to be based on a common disturbance of biological feedback systems. As a touchstone of classical ‘intermediate area’ in psychiatry the changing clinical picture of anorexia nervosa provokes a unitarian view of mental disease. It exemplifies a hesitant change of paradigm in an up till now dualistic conception of organic/biological and psychological models. This complementary approach tries to integrate psychic phenomena into a holistic understanding of complex psychopathological realities on the basis of qualitative and dimensional aspects in order to counteract the nowadays threatening loss of information in psychiatric phenomenology.