An account is given for non-psychiatric physicians of the psychodynamic, psychiatric, and psychoterapeutic aspects of obesity. A primarily psychoanalytic explanation is presented of the unconscious meanings that the words involved assume in children and "fixed" obese subjects with regression to the "oral stage" of their libido development. The meanings associated with food and feeding are examined in an interpersonal, familial, social and environmental context. A summary psychopathological classification is made of obesity, together with an evaluation of what appears to be the direct opposite of obesity, i. e. mental anorexia. Lastly, the relevant prognostic and therapeutic criteria are considered. The latter are mainly centred on the various forms of psychotherapeutic intervention (individual, group, analytical and inspiration therapy, etc.).