The goal of this interventional study is to prevent childhood obesity in children aged 6-12 years in Chiba City, Japan. The main questions it aims to answer are: * Does the multi-component intervention for environments around children reduce the BMI z-score of children aged 6-12 years after one and two years? * Does the multi-component intervention for environments around children improve the health-related quality of life (assessed by KIDSCREEN-10) of children aged 6-12 years after one and two years? Researchers will compare school clusters receiving the intervention to control clusters to see if the intervention package promotes healthy eating, increases physical activity, improves health-related quality of life, and reduces obesity prevalence. Participants will: * Attend elementary schools within participating clusters (either the intervention or control group). * Have baseline data collected, with follow-up assessments after one year and two years. * Potentially participate in school-based programs (nutrition education, physical activity promotion) and community-based initiatives (park activation, supermarkets) if in an intervention cluster. * Have their physical activity and dietary behavior assessed through self-report questionnaires.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
NONE
Enrollment
2,200
The CBH COPI intervention applies multi-level strategies to improve children's environments and foster healthy behaviors. In schools, activities include schoolyard enhancements (e.g., hopscotch), inter-school sports events, nutrition lectures, healthy snacks, and educational materials linking health and academics. In parks and roads, improvements include cycling/walking promotions, signage, healthier vending machines, and community events. Supermarkets support healthy choices through menu information, loyalty incentives, cooking classes, product placement, and healthy food sales. At home and in communities, the Min-Challe app supports habit formation, with athletes, mascots, and ambassadors promoting healthy living. The coordinated program aims to naturally promote healthy eating, physical activity, and sustained lifestyle change among children aged 6-12 in Chiba City.
Chiba University
Chiba, Chiba, Japan
Body mass index z-score (BMI-z) adjusted for age and sex
The primary outcome is the BMI z-score, calculated using the WHO 2007 Growth Reference. This metric standardizes a child's relative weight status by adjusting for both age and sex, enabling comparisons across different age groups and sexes. It represents the number of standard deviations a child's BMI is from the mean BMI of a healthy reference population. The BMI z-score allows for monitoring obesity-related changes over time and assessing the intervention's effectiveness in preventing excessive weight gain. The use of this z-score ensures consistency with international standards, facilitating global comparison of childhood obesity trends. The analysis will focus on changes in BMI z-score from baseline to 1-year and 2-year follow-ups.
Time frame: Baseline, 1-year follow-up, 2-year follow-up (2025-2027)
Health-Related Quality of Life (HRQoL)
HRQoL will be assessed using the KIDSCREEN-10 index, a validated, self-reported measure capturing children's subjective well-being across physical, emotional, social, and school functioning. This 11-item scale uses a 5-point Likert response for each item, which is then converted into a standardized T-score, further transformed to a 0-100 scale. On this scale, higher scores indicate better perceived quality of life. Changes in KIDSCREEN-10 scores will be tracked from baseline through 1-year and 2-year follow-ups to evaluate the intervention's impact on children's overall well-being.
Time frame: Baseline, 1-year follow-up, 2-year follow-up (2025-2027)
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