The contribution of lifestyle coaching of overweight patients in primary care to more autonomous motivation for physical activity and healthy dietary behaviour: results of a longitudinal study

Background: Combined lifestyle interventions (CLIs) have been advocated as an effective instrument in efforts to reduce overweight and obesity. The odds of maintaining higher levels of physical activity (PA) and healthier dietary behaviour improve when people are more intrinsically motivated to change their behaviour. To promote the shift towards more autonomous types of motivation, facilitator led CLIs have been developed including lifestyle coaching as key element. The present study examined the shift in types of motivation to increase PA and healthy dieting among participants of a primary care CLI, and the contribution of lifestyle coaching to potential changes in motivational quality. Methods: This prospective cohort study included participants of 29 general practices in the Netherlands that implemented a CLI named 'BeweegKuur'. Questionnaires including items on demographics, lifestyle coaching and motivation were sent at baseline and after 4 months. Aspects of motivation were assessed with the Behavioural Regulation and Exercise Questionnaire (BREQ-2) and the Regulation of Eating Behaviour Questionnaire (REBS). We performed a drop out analysis to identify selective drop-out. Changes in motivation were analysed with t-tests and effect size interpretations (Cohen's d), and multivariate regression analysis was used to identify predictors of motivational change. Results: For physical activity, changes in motivational regulation were fully in line with the tenets of Self Determination Theory and Motivational Interviewing: participants made a shift towards a more autonomous type of motivation (i.e. controlled types of motivation decreased and autonomous types increased). Moreover, an autonomy supportive coaching style was generally found to predict a larger shift in autonomous types of motivation. For healthy dietary behaviour, however, except for a small decrease in external motivation, no favourable changes in different types of motivation were observed. The relation between coaching and motivation appeared to be influenced by the presence of physical activity guidance in the programme. Conclusions: Motivation of participants of a real life primary care CLI had changed towards a more autonomous motivation after 4 months of intervention. Autonomy-supportive lifestyle coaching contributed to this change with respect to physical activity. Lifestyle coaching for healthy diet requires thorough knowledge about the problem of unhealthy dieting and solid coaching skills.