Current estimates suggest that approximately 32% of United States (US) adults are obese, with a body mass index (BMI) of 30 or greater, and 34% of adults are overweight, with a BMI of 25.0 to 29.9 [1, 2]. Preventing and treating obesity is a multifaceted problem that will likely need to be addressed on multiple levels ranging from policy to individual interventions. On the individual level, successful weight loss programs exist and the most beneficial are clinic-based face-to-face behavioral programs with weekly visits [3, 4]. Although effective, these programs tend to be costly, inaccessible to some, and inconvenient due to the time required and the need to travel to a clinic. These limitations decrease the potential public health impact of these programs. As a result, Internet-based weight loss programs, which have the potential to reach larger numbers of individuals, potentially at a lower cost, have become more common.
Self-directed Internet programs are effective in producing an average weight loss of 5.5 kg in the first six months of treatment compared to 8-10 kg of weight loss seen in face-to-face programs [3–5]. More frequent program utilization has been associated with better weight loss outcomes in Internet-based programs; however, over time utilization decreases [6, 7]. This decreasing utilization could be related to decreasing motivation levels. In an effort to improve outcomes in self-directed programs, participant motivation could be targeted and enhanced.
Self-Determination Theory (SDT) suggests that there are two different types of motivation, autonomous and controlled . Autonomous motivation is a measure of a person's internal or personal reasons for change, including all intrinsic reasons for change and some extrinsic reasons. Controlled motivation is a measure of the extent to which a person feels external pressures to change, similar to extrinsic motivation . SDT suggests that greater autonomous motivation is associated with greater likelihood of behavior change and high controlled motivation is associated with less likelihood of success with change . Previous research indicates that autonomous motivation is positively associated with greater physical activity and fruit and vegetable consumption; whereas, controlled motivation has no association or a negative association with these outcomes [10, 11]. Additionally, higher levels of autonomous motivation measured five to ten weeks into a weight loss program has been predictive of better 6-month weight loss and 23-month weight maintenance while greater controlled motivation was predictive of less weight loss at six months .
These motivational constructs may help us to gain an understanding of when and for whom our weight loss programs work. Because autonomous motivation is influential to physical activity, dietary behavior, and weight management, finding ways to increase autonomous motivation may be important for weight loss success and long term weight loss maintenance.
SDT suggests several ways in which motivation may be positively influenced. Autonomy, competence, and relatedness are the three central psychological needs specified by SDT. The support of these three needs can lead to greater autonomous regulation and motivation . Deci and Ryan, the authors of SDT, suggest that motivational interviewing (MI) , a type of counseling style, is conducive to supporting these three basic needs. The use of MI in various disciplines has led to improved program attendance, adherence, and retention [13–16]. At least one study has found that the use of MI principles in a weight loss program may lead to increases in autonomous motivation over time . Studies which have used MI techniques in weight loss treatments have shown mixed results on weight loss and none of these previous interventions have reported on motivation levels of participants at baseline or throughout the program [17–19].
Additionally, there are other intervention components that could be used to enhance autonomous motivation and improve weight loss. A sense of personal competence, or self-efficacy, can be enhanced through the accomplishment of small achievable goals [20, 21]. Therefore, personal goal setting in an autonomy supportive climate might also improve autonomous motivation. Finally, Deci and Ryan also suggest that greater mindfulness is associated with greater autonomous regulation . It is proposed that greater mindfulness may allow for integration of introjected or controlled reasons for change into a more autonomous mindset, thus leading to a decrease in controlled motivation and an increase in autonomous motivation. Therefore, an intervention component that encourages mindfulness might also increase autonomous motivation and weight loss.
The aim of the present study was to determine if a motivation-enhanced behavioral weight loss intervention, which incorporated principles of MI, personal goal setting, and journaling, resulted in greater weight loss, greater program usage, and greater increases in autonomous motivation than a standard behavioral weight loss program. An additional aim was to determine whether baseline levels of autonomous and controlled motivation moderated the effect of the two interventions on weight loss.