A systematic review of motivational interviewing for weight loss among adults in primary care

Motivational interviewing (MI) is a client-centred method of intervention focused on enhancing intrinsic motivation and behaviour change. A previous review of the literature and meta-analyses support the effectiveness of MI for weight loss. None of these studies, however, focused on the bourgeoning literature examining MI for weight loss among adults within primary care settings, which confers unique barriers to providing weight loss treatment. Further, the current review includes 19 studies not included in previous reviews or meta-analyses. We conducted a comprehensive review of PubMed, MI review papers, and citations from relevant papers. A total of 24 adult randomized controlled trials were identified. MI interventions typically were provided individually by a range of clinicians and compared with usual care. Few studies provided adequate information regarding MI treatment fidelity. Nine studies (37.5%) reported significant weight loss at post-treatment assessment for the MI condition compared with control groups. Thirteen studies (54.2%) reported MI patients achieving at least 5% loss of initial body weight. There is potential for MI to help primary care patients lose weight. Conclusions, however, must be drawn cautiously as more than half of the reviewed studies showed no significant weight loss compared with usual care and few reported MI treatment fidelity.