Background Currently, the effects of motivational interviewing (MI) on children’s behavioral changes remain obscure. Purpose This systematic review and meta-analysis examined the effects of MI on children’s lifestyle behavioral changes (fruits and vegetables [F/V], dairy, sugary beverages, calories, snacks, fat intake, moderate vigorous physical activity [MVPA], and screen time). Methods Six databases (CINAHL, Cochrane, Embase, PsycINFO, PubMed, and Web of Sciences) from 2005 to 2022 were searched. Thirty-one intervention studies with a comparison group met the criteria. Random-effects models were performed to estimate the pooled effects; exploratory moderation analyses with mixed-effects models were used to explore potential intervention moderators. Results The pooled effect size was 0.10 (p = .334) on ↑F/V, 0.02 (p = .724) on ↑dairy, −0.29 (p < .001) on ↓calories, −0.16 (p = .054) on ↓sugary beverages, −0.22 (p = .002) on ↓snacks, −0.20 (p = .044) on ↓fat, 0.22 (p = .001) on ↑MVPA, and −0.06 (p = .176) on ↓screen time. The effects of MIs were moderated by ↑MI sessions regarding ↓snacks (B = −0.04, p = .010). Multicomponent and clinical programs had greater effects on dairy intake than their counterparts (0.09 vs. −0.21, p = .034; 0.12 vs. −0.14, p = .027, respectively). Similarly, interventions with a fidelity check resulted in greater dairy intake than those without a check (0.29 vs. −0.15, p = .014). A few long-term follow-up assessments revealed effects on ↓F/V (−0.18; p = .143, k = 2), ↓dairy (−0.13, p = .399, k = 4), ↓MVPA (−0.04; p = .611, k = 6), and ↑screen time (0.12; p = .242, k = 4). Conclusions Our findings support the short-term effects of MI on improving children’s lifestyle behaviors. Additional investigations are needed to better sustain children’s long-term behavioral changes.

Summary 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%).