The effects of motivational interviewing on children's body mass index and fat distributions: A systematic review and meta-analysis

Currently, the effects of motivational interviewing (MI) on children's anthropometric changes remain unclear. This systematic review and meta-analysis examined the effects of MI on children's anthropometric changes (body mass index [BMI], waist circumference [WC], and body fat percentage [BF%]). We also assessed potential moderators of MI on children's BMI changes. This systematic review searched five databases (CINAHL, Cochrane, PsycINFO, PubMed, and Web of Sciences) from 2005 to 2020 to evaluate the effects of MI interventions that had a comparison group on children's anthropometric change as outcomes (BMI, WC, or BF%). Thirty-three articles met the inclusion criteria. We performed random-effects models and exploratory moderation analyses with mixed-effects models. The pooled effect size of MI was -0.18 (p = 0.002) on BMI, -0.65 (p < 0.001) on WC, and -0.44 (p = 0.005) on children's BF%. The relationship between MI and BMI changes was significantly moderated by the types of intervener (Q = 9.71, p = 0.021) and the existence of supplemental intervention activities (Q = 9.21, p = 0.002). Other potential moderators included children's age, weight status, intervention setting, and targeted behaviors (eating and/or physical activity). Our findings support the effectiveness of MI interventions on improving children's anthropometric outcomes (i.e., BMI, WC, and BF%).