The prevalence of child and adolescent obesity has been a major worldwide problem for decades. To stop the number of youth with overweight/obesity from increasing, numerous interventions focusing on improving children's weight status have been implemented. The growing body of research on weight-related interventions for youth has been summarized by several meta-analyses aiming to provide an overview of the effectiveness of interventions. Yet, the number of meta-analyses is expanding so quickly and overall results differ, making a comprehensive synopsis of the literature difficult. To tackle this problem, a meta-synthesis was conducted to draw informed conclusions about the state of the effectiveness of interventions targeting child and adolescent overweight. The results of the quantitative synthesis of 26 meta-analyses resulted in a standardized mean difference (SMD) of -0.12 (95%CI: -0.16, -0.08). Several moderator analyses showed that participant and intervention characteristics had little impact on the overall effect size. However, a moderator analysis distinguishing between obesity treatment and obesity prevention studies showed that obesity treatment interventions (SMD: -0.048, 95%CI: -0.60, -0.36) were significantly more effective in reducing body mass index than obesity prevention interventions (SMD: -0.08, 95%CI: -0.11, -0.06). Overall, the results of this meta-synthesis suggest that interventions result in statistically significant effects albeit of relatively little clinical relevance.