The role of self-determination theory and motivational interviewing in behavioral nutrition, physical activity, and health: an introduction to the IJBNPA special series

The links between SDT, a well-established theory of human motivation and behavior, and MI, a popular clinical method for evoking behavior change are multiple and have been explored before [5,6], leading many to think that a formal "marriage" - i.e., accepting SDT as "the theory of MI" and MI as the "intervention method of SDT" - would be just a matter of time. Both models are explicitly person-centered and process-oriented, both emphasize that optimal behavior change must involve deep personal commitment and engagement, and both stress that a positive emotional "climate", defined by genuine empathy and unconditional regard towards patients or clients is a necessary condition for the success of behavior change interventions, especially their long-term effects. Moreover, both SDT and MI appear to have at its center the concept of motivation, endorsing the development of "internal" motives and the need for patients to take responsibility for change, to the detriment of externally imposed goals, pressures, or a preponderance of reasons for change which are nor personally meaningful [7,8].The interest in both MI and SDT has grown steadily over the past decades, with scholars and practitioners working in fields such as eating behavior (e.g., [9]), physical activity (e.g., [10]), and diabetes (e.g. [11]), becoming increasingly interested in exploring motivational dynamics. It is recognized that the motivation underlying patients' behavior change attempts provides them the necessary energy to actually undertake change and plays a key role in successful long-term outcomes. In fact, the issue of behavioral persistence is a critical one in the era of behavioral, preventive, and "lifestyle" medicine, with individuals increasingly called upon to manage or "self-regulate" their own health [12]. Short-lived change, such as what results from so many weight loss programs, is not what health practitioners and their patients are usually looking for.According to SDT, although patients