Effectiveness of a Socioecological School‐Based 24‐h Movement Behaviour Intervention on Lifestyle Behaviours Among Children and Adolescents With Overweight or Obesity: A Gender‐Stratified Quasi‐Experimental Study

Background Childhood obesity and inadequate physical activity are major public health concerns in Pakistan. Evidence on multicomponent school‐based interventions targeting 24‐h movement behaviours, particularly with gender‐specific approaches, remains limited. Methods A 12‐week quasi‐experimental cluster‐controlled study was conducted in eight public schools in Lahore, Pakistan. A total of 1200 children and adolescents (577 boys, 623 girls; aged 9–17 years) were assigned to an intervention group ( n = 570) or a control group ( n = 630). The intervention, guided by the socioecological model, included enhanced physical education, extracurricular physical activity, health education, parental engagement and supportive school environments. Outcomes included anthropometric measures and 24‐h movement behaviours. Intervention effects were analysed using repeated‐measures analysis of variance (ANOVA) and general linear mixed models ( p < 0.05). Results Significant group‐by‐time interactions were observed for physical activity ( η 2 = 0.28), screen time ( η 2 = 0.15), sleep duration ( η 2 = 0.16) and fast‐food consumption ( η 2 = 0.07) (all p < 0.001). The prevalence of overweight and obesity among children and adolescents declined from 31.0% to 28.0% in the intervention group but increased from 36.0% to 38.0% in the control group ( p = 0.005). Physical activity guideline adherence increased from 26.3% to 71.8% among boys and from 22.2% to 63.3% among girls (both p < 0.001). Significant reductions in BMI, waist circumference and waist‐to‐height ratio were also observed in the intervention group. Conclusions A multicomponent, socioecological, school‐based intervention effectively improved movement behaviours, dietary habits, parental support and outcomes related to overweight and obesity among Pakistani children and adolescents. These findings support integrated school‐ and family‐based strategies for preventing childhood obesity across both boys and girls.