Childhood obesity has become a major global public health challenge. Obesity can not only affects children's physical and mental health during childhood but may also persist into adulthood, significantly increasing the risk of cardiovascular disease. Therefore, effective prevention and control of childhood obesity can shift the prevention window forward and promote the prevention of cardiovascular disease. Recently, time-restricted eating (TRE) has gained attention in adult studies for its feasibility, as it involves "time control without calorie restriction," demonstrating weight loss effects comparable to energy restriction and higher feasibility. Here, the investigators designed a school-based cluster randomized controlled trial to investigate the effectiveness of 12-hour TRE in preventing and controlling childhood obesity. Schools were randomly assigned to either the intervention group or the control group, and participants were recruited from each school at the class level, ensuring that each group included at least 690 children. The control group received routine health education, while the intervention group received 12-hour TRE in addition to routine health education. After a 9-month intervention period (one academic year), the two groups will be compared in terms of weight management and childhood obesity prevalence.

Childhood obesity has become a major global public health challenge. With rapid economic development, the prevalence of childhood obesity in China has risen from 0.1% in 1985 to 7.3% in 2024. Childhood obesity not only affects children's physical and mental health during childhood but may also persist into adulthood, significantly increasing the risk of cardiovascular disease. Therefore, effective prevention and control of childhood obesity can shift the prevention window forward and promote the prevention of cardiovascular disease. The age distribution of childhood obesity shows that the peak incidence occurs between 7 and 12 years of age, making this a critical period for prevention and control. During this stage, children are in school, spending half their time there, and exhibit strong behavioral plasticity. Interventions based on school settings may be an effective approach to preventing and controlling childhood obesity. Previous experimental studies have shown that comprehensive school-based interventions (primarily including reducing overeating, high-energy diets, and sedentary behavior, while increasing physical activity) can significantly reduce BMI and childhood obesity prevalence, but their feasibility is limited. Recently, time-restricted eating (TRE) has gained attention in adult studies for its feasibility, as it involves "time control without calorie restriction," demonstrating weight loss effects comparable to energy restriction and higher feasibility. Therefore, the investigators hypothesize that a 12-hour TRE program implemented in schools may enhance the prevention and control of childhood obesity, but there is currently a lack of empirical evidence, particularly regarding its preventive effects on childhood obesity. Here, the investigators designed a school-based cluster randomized controlled trial to investigate the effectiveness of 12-hour TRE in preventing and controlling childhood obesity. Schools were randomly assigned to either the intervention group or the control group, and participants were recruited from each school at the class level, ensuring that each group included at least 690 children. The control group received routine health education, while the intervention group received 12-hour TRE in addition to routine health education. After a 9-month intervention period (one academic year), the two groups will be compared in terms of weight management and childhood obesity prevalence.

Eligibility criteria for schools:

1. The principal agrees to accept the randomization process and adhere to the study protocol;
2. The total number of fourth-year students in the school must be more than 50;
3. Schools that have not implemented or plan to implement obesity prevention interventions;
4. Non-boarding schools, Ethnic minority schools, or specialty schools;
5. Schools that have no clear plans to relocate or close within the next 2 years;

Eligibility criteria for classes:

1. Class teachers are willing and actively involved in home-school liaison;
2. Class sizes should be between 30 and 60 students;
3. The class consists of fourth-grade students;
4. Classes that have no clear plan to merge or cancel in the next 2 years;

Exclusion criteria for students:

All students in the selected classes will be the subject of the study after signing the informed consent, unless they have the following circumstances:

1. Individuals with a history of heart disease, high blood pressure, diabetes, tuberculosis, asthma, hepatitis or nephritis;
2. Individuals with secondary obesity: obesity due to endocrine disorders or side effects of medications;
3. Individuals with abnormal growth and development, such as dwarfism, gigantism, etc;
4. Individuals with physical deformities, including severe scoliosis, chicken breasts, claudication, significant O-leg/X-shaped legs;
5. Individuals with limited athletic ability who are unable to participate in school physical activities;
6. Individuals who have lost weight by inducing vomiting or taking medication in the past 3 months;
7. Individuals who have undergone prior bariatric surgery;
8. Individuals with mental disorders or intellectual developmental disabilities, as well as aphasia;
9. Individuals who have taken medications that affect appetite or weight within three months (e.g., antipsychotics, hypnotics, weight loss medications, insulin);
10. Individuals who have plans to transfer within 2 years;

The unidentified patient data can be shared.