Physical activity interventions (PAIs) are often recommended to ameliorate childhood obesity, but the effectiveness of theory-based PAIs remains unclear. This study aimed to synthesize evidence and quantify the impact of theory-based PAIs on body mass index (BMI) and BMI z-score in this population.

Literature published between January 2009 and August 2025 was searched from five databases (Medline, Scopus, Cochrane, Embase, and Web of Science). The quality of articles was assessed with the Jadad scale, and Meta-analysis was performed using RevMan 5.3. Random-effects models were used to estimate the combined effect size (standardized mean difference [SMD]), and subgroup analyses were conducted along different dimensions (age, intervention duration, family engagement approach, and theory type).

19 studies met the research criteria. there were 15 studies based on 1 theory, whereas 4 studies were based on multiple theories, with social-cognitive theory being the most commonly practiced. The quality of articles included in this review was generally moderate, and significant improvements in theory-based PAIs were found for SMD by -0.15% (95% confidence interval [CI] = -0.26, -0.04; P = 0.008). Moreover, subgroup analyses revealed that younger participant age, longer intervention duration, deeper family engagement roles, and application of the theory of planned behavior may have more positive effects.

Theory-based PAIs are associated with improvements in childhood obesity, and we recommend that favorable elements of interventions and integration of theoretical frameworks should be fully leveraged in future research to improve the health and well-being of children and adolescents.