Family-Centered mHealth Intervention via a WeChat Mini-Program for Children with Overweight or Obesity: Protocol for a Two-Arm Cluster Randomized Controlled Trial (Preprint)

<sec> <title>BACKGROUND</title> <p>Childhood overweight and obesity remain pressing public health challenges worldwide. Although e-health interventions have shown promise for pediatric obesity treatment, few family-centered digital programs have been delivered through widely adopted social media platforms.</p> </sec> <sec> <title>OBJECTIVE</title> <p>This protocol describes a cluster randomized controlled trial evaluating the efficacy of a 10-week family-focused intervention delivered via an interactive WeChat mini-program for children with overweight or obesity.</p> </sec> <sec> <title>METHODS</title> <p>The trial was initiated in March 2026, enrolling 126 children with overweight or obesity from 16 classes across two primary schools in Shandong Province, China. Classes were randomly assigned in a 1:1 ratio to either the WeChat mini-program intervention or a usual health education control group. Assessments are conducted at baseline, post‑intervention (10 weeks), and at 3-month follow-up. The primary outcome is the change in children's proactive health behaviors. Secondary outcomes include changes in BMI, waist circumference, waist-to-height ratio, and family intergenerational transmission factors (e.g., parent-child communication, family cohesion, and family functioning).</p> </sec> <sec> <title>RESULTS</title> <p>As of May 2026, all 126 enrolled children had completed baseline assessments and undergone randomization (intervention: n=61; control: n=65). The mean age was 11.21 years (SD 0.78); 65.1% (82/126) were male and 34.9% (44/126) were female. Median BMI was 23.41 kg/m² (Q1, Q3: 22.06, 25.15), and mean waist-to-height ratio was 0.54 (SD 0.05). Most participants lived with both parents (74.6%, 94/126), and nearly half of fathers (45.2%, 57/126) and mothers (44.4%, 56/126) had a college education or higher. Baseline characteristics were generally balanced between the two groups. Data collection is ongoing, with analysis expected to begin in October 2026. The trial is registered with the Chinese Clinical Trial Registry (ChiCTR2600116725).</p> </sec> <sec> <title>CONCLUSIONS</title> <p>This protocol describes a theory-driven, rigorously designed, and broadly applicable e-health intervention. If proven effective, it has the potential for widespread dissemination through the existing WeChat ecosystem to support childhood obesity management in real-world settings.</p> </sec> <sec> <title>CLINICALTRIAL</title> <p>Chinese Clinical Trial Registry (ChiCTR2600116725); Registered in January 2026; https://www.chictr.org.cn/bin/project/edit?pid=303839</p> </sec>