Behavior change is more effective and lasting when patients are autonomously motivated. To examine this idea, we identified 184 independent data sets from studies that utilized self-determination theory (SDT; Deci & Ryan, 2000) in health care and health promotion contexts. A meta-analysis evaluated relations between the SDT-based constructs of practitioner support for patient autonomy and patients' experience of psychological need satisfaction, as well as relations between these SDT constructs and indices of mental and physical health. Results showed the expected relations among the SDT variables, as well as positive relations of psychological need satisfaction and autonomous motivation to beneficial health outcomes. Several variables (e.g., participants' age, study design) were tested as potential moderators when effect sizes were heterogeneous. Finally, we used path analyses of the meta-analyzed correlations to test the interrelations among the SDT variables. Results suggested that SDT is a viable conceptual framework to study antecedents and outcomes of motivation for health-related behaviors.

Self-determination theory proposes that behavior change will occur and persist if it is autonomously motivated. Autonomous motivation for a behavior is theorized to be a function both of individual differences in the autonomy orientation from the General Causality Orientations Scale and of the degree of autonomy supportiveness of relevant social contexts. We tested the theory with 128 patients in a 6-month, very-low-calorie weight-loss program with a 23-month follow-up. Analyses confirmed the predictions that (a) participants whose motivation for weight loss was more autonomous would attend the program more regularly, lose more weight during the program, and evidence greater maintained weight loss at follow-up, and (b) participants' autonomous motivation for weight loss would be predicted both by their autonomy orientation and by the perceived autonomy supportiveness of the interpersonal climate created by the health-care staff. Recent statistics indicate that more than 12 million American adults are severely obese and face significant health risks due to their weight (Kissebah, Freedman, & Peiris, 1989; Kuczmarski, 1992). ~ In addition to being linked to heart disease, hypertension, diabetes, and various other illnesses, severe obesity has been found, in both longitudinal and actuarial studies, to significantly increase the risk of premature death (Drenick, Bale, & Seizer, 1980; Pi-Sunyer, 1993; Simopoulos & Van Itallie, 1984). Furthermore, in many countries, including the United States, obesity is a stigmatizing condition, especially for women (Sobal & Stunkard, 1989), and is often associated with dysphoric states and psychological problems. Although there is disagreement about whether or not there are significant risks associated with mild obesity (Garner & Wooley, 1991), there is little doubt about the seriousness of the risks associated with severe and morbid obesity. 2 Consequently, very-low-calorie diets have often been recommended for the severely or morbidly obese. Although such diets can have negative side effects (e.g., Apfelbaum, Fricker, & Igoin-Apfelbaum, 1987), the risks related to severe and morbid obesity are believed to outweigh those related to the diets. Typically, people who persist at very-low-calorie diets lose large amounts of weight, averaging about 44 lbs (20 kg) in 12-16 weeks (Wadden, 1993). The great majority of these individuals, however, regain a substantial portion of that weight within

The findings support the prediction of the self-determination theory that patients with diabetes whose health care providers are autonomy supportive will become more motivated to regulate their glucose levels, feel more able to regulate their glucose, and show improvements in their HbA1c values.

Two studies tested self-determination theory with 2nd-year medical students in an interviewing course. Study 1 revealed that (a) individuals with a more autonomous orientation on the General Causality Orientation Scale had higher psychosocial beliefs at the beginning of the course and reported more autonomous reasons for participating in the course, and (b) students who perceived their instructors as more autonomy-supportive became more autonomous in their learning during the 6-month course. Study 2, a 30-month longitudinal study, revealed that students who perceived their instructors as more autonomy-supportive became more autonomous in their learning, which in turn accounted for a significant increase in both perceived competence and psychosocial beliefs over the 20-week period of the course, more autonomy support when interviewing a simulated patient 6 months later, and stronger psychosocial beliefs 2 years later.

PurposeThis systematic review aims to explain the heterogeneity in results of interventions to promote physical activity and healthy eating for overweight and obese adults, by exploring the differential effects of behaviour change techniques (BCTs) and other intervention characteristics.MethodsThe inclusion criteria specified RCTs with ≥ 12 weeks’ duration, from January 2007 to October 2014, for adults (mean age ≥ 40 years, mean BMI ≥ 30). Primary outcomes were measures of healthy diet or physical activity. Two reviewers rated study quality, coded the BCTs, and collected outcome results at short (≤6 months) and long term (≥12 months). Meta-analyses and meta-regressions were used to estimate effect sizes (ES), heterogeneity indices (I2) and regression coefficients.ResultsWe included 48 studies containing a total of 82 outcome reports. The 32 long term reports had an overall ES = 0.24 with 95% confidence interval (CI): 0.15 to 0.33 and I2 = 59.4%. The 50 short term reports had an ES = 0.37 with 95% CI: 0.26 to 0.48, and I2 = 71.3%. The number of BCTs unique to the intervention group, and the BCTs goal setting and self-monitoring of behaviour predicted the effect at short and long term. The total number of BCTs in both intervention arms and using the BCTs goal setting of outcome, feedback on outcome of behaviour, implementing graded tasks, and adding objects to the environment, e.g. using a step counter, significantly predicted the effect at long term. Setting a goal for change; and the presence of reporting bias independently explained 58.8% of inter-study variation at short term. Autonomy supportive and person-centred methods as in Motivational Interviewing, the BCTs goal setting of behaviour, and receiving feedback on the outcome of behaviour, explained all of the between study variations in effects at long term.ConclusionThere are similarities, but also differences in effective BCTs promoting change in healthy eating and physical activity and BCTs supporting maintenance of change. The results support the use of goal setting and self-monitoring of behaviour when counselling overweight and obese adults. Several other BCTs as well as the use of a person-centred and autonomy supportive counselling approach seem important in order to maintain behaviour over time.Trial RegistrationPROSPERO CRD42015020624 Electronic supplementary materialThe online version of this article (doi:10.1186/s12966-017-0494-y) contains supplementary material, which is available to authorized users.