Effectiveness of interventions using Motivational Interviewing for dietary and physical activity modification in adults: a systematic review

Background When healthcare professionals are confronted with ambivalence in their clients, traditional advice‐giving can be counter‐productive. Motivational Interviewing (MI), an alternative to traditional advice‐giving, aims to provide the ambivalent client with a supportive, non‐judgmental environment in which to discuss the possibility of change. Objectives This review aimed to synthesize the best available evidence on the effectiveness of dietary and physical activity interventions employing MI to achieve behavior change. Inclusion criteria Types of participants The review included participants aged 18 years or older. Types of intervention(s)/phenomena of interest Studies that defined the intervention as ‘Motivational Interviewing’ and provided detail on how MI was incorporated into the studies were included. The included studies separated subjects into one group receiving the MI intervention and one group receiving a comparison treatment with similar contact but without MI counseling (an attention control). Types of studies The review considered randomized controlled trials (RCT) or systematic reviews published in English between 1980 to January 2012 Types of outcomes Outcomes of interest included diet (energy intake, core food groups, macronutrient composition of the diet, diet quality or diet index) and/or physical activity including exercise or sedentary behaviors (energy expenditure, steps taken, minutes of physical activity or sitting time). Search strategy Nine databases were searched and the reference lists of all included studies were searched for additional studies not previously identified. Methodological quality Two independent reviewers used a standardized appraisal tool to ensure the methodological quality of the studies. Data collection Two reviewers performed data extraction using a standardized tool. Data synthesis A qualitative synthesis was undertaken through a comparative narrative summary. Results The search yielded 1,765 articles of which eight met all inclusion criteria. The review reported on a heterogeneous sample of studies that were of low‐to‐moderate quality. Five of the studies reported monitoring MI fidelity; however only three studies reported proficiency scores. Two of the five articles reporting on diet found positive effects. One study found a lower saturated fat score in the group that received MI by a dietician (&bgr;=0.23, &rgr;<0.01) compared with counseling by a dietician not trained in MI. The other study reported a significant difference in percent energy from fat (2.6%, &rgr;<0.001) favoring Motivational Interviewing when comparing Motivational Interviewing from a dietician versus standard care. None of the six articles reporting on physical activity found any difference between MI and the attention control. Conclusions There is not yet sufficient evidence to conclude that MI enhances diet and physical activity behavior change above an attention control, although the findings from two studies are suggestive of a positive effect in decreasing dietary fat intake. Implications for practice When more high quality research evidence is available, the next challenge will be to establish evidence that research‐based interventions will translate to the clinical setting. Implications for research More high quality studies that objectively measure diet and physical activity, evaluate and report fidelity scores and compare a MI intervention to an attention control over a period of at least six months are required.