After-School to Pre-Sleep Energy Restriction for obesity in primary school children in grades 3–6: protocol for a parallel, randomized controlled trial

Abstract Background The rising prevalence of childhood obesity has become a major global public health concern. Dietary intervention remains the cornerstone of pediatric obesity management. However, both conventional all-day energy-restricted diets and time-restricted eating have limitations in school-aged children. Studies indicate that excessive evening caloric intake is closely associated with obesity. This trial aims to evaluate the efficacy of an After-School to Pre-Sleep Energy Restriction (ASER) strategy compared with standard dietary intervention for pediatric obesity management. Methods and analysis This study is a prospective, randomized, open-label, parallel-group trial. We plan to enroll 164 obese children from grades 3 to 6, who will be stratified by age, gender, and BMI z -score and randomly assigned in a 1:1 ratio to either the ASER group or the control group. The 24-week intervention consists of an intensive phase (weeks 0–12) followed by a maintenance phase (weeks 13–24). The primary endpoint is the between-group difference in BMI z -score (BMIz) change at week 12. Secondary endpoints include within-group BMIz changes at week 12; between-group and within-group BMIz changes at week 24; between-group and within-group changes in %BMI 95 , body composition, growth parameters, cardiometabolic markers, and psychobehavioral metrics at both 12 and 24 weeks; and between-group differences in the incidence of adverse events at weeks 12 and 24. Ethics and dissemination This study was approved by the Medical Ethics Committee of the First Affiliated Hospital of Guangxi Medical University (Approval No.: 2025-K0254). Written informed consent will be obtained from legal guardians, and assent will be obtained from child participants prior to enrollment. Study findings will be published in peer-reviewed journals. Trial registration The trial was prospectively registered on 3 September 2025, prior to the first participant enrollment, with the Chinese Clinical Trial Registry (ChiCTR2500108702). The URL of the specific trial registry record is https://www.chictr.org.cn/showproj.html?proj=275435 .