Group motivational interviewing in the “small changes” weight management project: A quasi-experimental trial
Trevor Simper, Jeff Breckon, Karen Kilner
Background: Motivational interviewing (MI) has been recommended as an effective counseling intervention for weight management with overweight and obese individuals. Nevertheless, there is a paucity of research for the use of MI in weight management groups and research in the area often lacks sufficient “treatment fidelity (TF),” failing to accurately report the consistency, style, content and competence of those delivering the intervention. The current study examined the efficacy of the small changes weight management program comparing MI in groups to treatment as usual. Methods: Those in the MI group intervention received 12 sessions of 2 h, which comprised 9 group and 3 one to one sessions over 12 months. The MI group was treated in MI consistent manner throughout; for example, change talk was identified, evoked, and strengthened via specific microskills such as open questions, affirmations, and reflections. In the treatment as a usual group, subjects also received 9 group and 3 one to one sessions over a 12-month period. The treatment as usual group was required to self-select a “small change” at each meeting with the facilitator. All subjects were measured at 5-time points: Baseline, 3, 6, 9, and 12 months, outcome measures included: Weight, body mass index, body fat percentage, waist to hip ratio (WHR), number of minutes of daily physical activity, fruit and vegetable consumption and feelings of well-being. A TF framework was applied to the MI groups’ intervention to ensure a consistent, reliable and reproducible approach. Results: After 12 months, improvements were shown for all variables measured in the MI groups; only the composite measure of physical and psychological wellbeing improved statistically in the treatment as usual groups. When comparing approaches: Significant differences were found between MI and treatment as usual in favor of the MI intervention for the mean percentage change in weight and body mass index but not for % body fat, WHR, fruit and vegetable consumption, feelings of well-being or physical activity levels. The retention rates in the MI groups were higher with 64% of subjects returning for the 12 months outcome measures versus 14% in the treatment as usual groups. Conclusions: This study indicates improvements to weight loss outcome measures after 12 months for an intervention implementing MI for weight management groups when compared to an existing weight management program. Future research is needed to establish the empirical basis for the use of MI for weight management groups, with the heterogeneity of dose and TF as essential features.