Historically, State Registered Dietitians have not received in-depth training in behaviour change skills. Training in this area has been viewed as peripheral rather than fundamental. Whilst a permanent long-term cure for obesity remains elusive, cognitive behavioural therapy is state of the art in the treatment of obesity. It reliably achieves 10% pretreatment body weight loss in the short-term. Interesting new developments are occurring in this field which may affect long-term outcome favourably. This paper examines what can be achieved with traditional dietary therapy in the treatment of obesity, what can be achieved with cognitive behavioural therapy and considers whether dietitians should receive further training in key behaviour change theory and skills. It is recommended that the integration of the fields of nutrition and behavioural psychology is placed centrally on the agenda of State Registered Dietitians.