Effectiveness of School-Based Time-Restricted Eating for the Prevention and Control of Obesity in Children: A Cluster-Randomized Controlled Trial
Phase: NA
Conditions: Childhood Obesity, Childhood Obesity Pevention
Sponsor: Children's Hospital of Soochow University

 
1
 
 
Effectiveness of School-Based Time-Restricted Eating for the Prevention and Control of Obesity 
in Children: A Cluster-Randomized Controlled Trial 
(SCHOOL-TRE) 
 
Study Protocol 
 
 
 
 Version: 3.0 
Version date: August 10, 2025 
 
 
 
 
 
Children's Hospital of Soochow University 
School of Public Health, Medical College of Soochow University

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Contents 
1. Summary ............................................................................................................................... 2 
2. Background ............................................................................ Error! Bookmark not defined. 
3. Study Design .......................................................................... Error! Bookmark not defined. 
4. Objectives .............................................................................. Error! Bookmark not defined. 
5. Study Subjects ........................................................................ Error! Bookmark not defined. 
6. Randomization and Recruitment ............................................ Error! Bookmark not defined. 
7. Interventions........................................................................... Error! Bookmark not defined. 
8. Data Collection ...................................................................... Error! Bookmark not defined. 
9. Dietary Intervention Monitoring System ............................... Error! Bookmark not defined. 
10. Methods of Data Measurement ............................................ Error! Bookmark not defined. 
11. Outcomes.............................................................................. Error! Bookmark not defined. 
12. Assessment of Outcomes...................................................... Error! Bookmark not defined. 
13. Statistical Power and Sample Size ....................................... Error! Bookmark not defined. 
14. Data management ................................................................. Error! Bookmark not defined. 
15. Statistical Analysis Plan ....................................................... Error! Bookmark not defined. 
16. Quality Control .................................................................... Error! Bookmark not defined. 
17. Security Monitoring ............................................................. Error! Bookmark not defined. 
18. Research Organization ......................................................... Error! Bookmark not defined. 
19. Ethical considerations .......................................................... Error! Bookmark not defined. 
20. Schedule ............................................................................... Error! Bookmark not defined. 
21. Reference ............................................................................. Error! Bookmark not defined. 
 
 
 
 
 

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1. Summary 
Title 
Effectiveness of School-Based Time-Restricted Eating for the Prevention 
and Control of Obesity in Children: A Cluster-Randomized Controlled Trial 
Background 
The prevalence of childhood obesity in China has risen from 0.1% in 1985 
to 7.3% in 2024. It does not only affect children's physical and mental health 
during childhood but also persist into adulthood, significantly increasing the 
risk of cardiovascular disease (CVD). Therefore, effective prevention and 
control of childhood obesity can shift the prevention window forward and 
promote the prevention of CVD. Childhood obesity is highly prevalent 
between 7 and 12 years of age, when children are spending half their time at 
school and exhibiting strong behavioral plasticity, making this a critical 
period for prevention and control of this debilitating disorder. Previous trials
have demonstrated 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, 
we 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. 
Objectives 
The overall objective of this study is to test the effectiveness of 12-hour TRE 
on the prevention and control of childhood obesity in school-aged children. 
The secondary objective is to test its long-term weight-controlling effect in 
children. 
Study Design 
The SCHOOL-TRE study is a school-based cluster randomized controlled 
trial designed to investigate the effectiveness of 12-hour TRE in the 
prevention and control of obesity in children. Schools were randomly 

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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 (8-10 years old). The control group 
received routine health education, while the intervention group received 12-
hour TRE in addition to routine health education. The primary effect of TRE 
will be evaluated after a 9-month intervention period (one academic year) by
comparing the magnitude of BMI-Z reduction from baseline between the two 
groups. Then, the intervention will be stopped, but the follow-up will be 
extended to one additional academic year to test its long-term effects. 
Study Subjects
Eligibility criteria for schools: 
 The principal agrees to accept the randomization process and adhere 
to the study protocol. 
 The total number of fourth-year students in the school must be over
50. 
 Schools that have not implemented or plan to implement obesity 
prevention interventions. 
 Non-boarding schools, Ethnic minority schools, or specialty schools. 
 Schools that have no clear plans to relocate or close within the next 2 
years. 
Eligibility criteria for classes: 
 Class teachers are willing and actively involved in home-school 
liaison. 
 Class sizes should be between 30 and 60 students. 
 The class consists of fourth-grade students. 
 There is at least one student with childhood obesity. 
 Classes that have no clear plan to be merged or canceled in the next 
2 years. 
Exclusion criteria for students: 
All students in the classes selected will be the subjects of the study after 
signing the informed consents, unless they have the following conditions: 

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 Students with a history of heart disease, hypertension, diabetes, 
tuberculosis, asthma, hepatitis, or nephritis. 
 Students with secondary obesity due to endocrine disorders or side 
effects of medications. 
 Students with abnormal growth development, such as dwarfism, 
gigantism, etc. 
 Students with physical deformities, including severe scoliosis, 
chicken breasts, claudication, and significant O-leg/X-shaped legs. 
 Students with limited athletic ability or an inability to participate in 
physical activities. 
 Students who have lost weight by inducing vomiting or taking 
medications in the past 3 months. 
 Students who have undergone bariatric surgery. 
 Students with 
mental disorders, 
intellectual 
developmental 
disabilities, or aphasia. 
 Students who have taken medications that affect appetite or weight 
within three months (e.g., antipsychotics, hypnotics, weight loss 
medications, insulin). 
 Students who plan to transfer in the next 2 years. 
Interventions 
Interventions for the control group: 
The current standard health education programs will be adopted according to
the Chinese guidelines for health education in primary and secondary 
schools. 
Interventions for the experimental group: 
In addition to the standard health education programs, the subjects in the 
experimental group will also receive training in 12-hour TRE. The core 
contents of 12-hour TRE include (1) the eating time window is limited to 12 
hours/day, (2) the last meal is no later than 19:00, (3) the subjects can freely 
choose the eating time window, (4) the subjects do not restrict energy intake 

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during eating window, and (5) the subjects are allowed to drink non-calorie, 
sugar-free drinks (water, tea, coffee) during the fasting period. 
Outcomes 
The short-term outcome is the magnitude of weight loss after one academic 
year (9 months) of intervention, and then the intervention will be stopped, 
but the follow-up will be extended to one additional academic year (21 
months) to test its long-term effects on obesity prevention. 
Primary outcome： 
Change in BMI-Z score from baseline to the end of 9 months of 
intervention 
Secondary outcome： 
 
Change in BMI-Z score from baseline to the end of 21 months after 
intervention 
 
Change in the prevalence of overweight or obesity 
 
Weight attainment (BMI-Z<2) rate 
 
Change in blood pressure 
 
Change in waist-to-hip ratio 
 
Change in quality of life 
 
Change in eating behavior 
 
Change in physical activity 
Sample Size 
The DECIDE-Children study demonstrated that a comprehensive school-
based intervention reduced BMI-Z values by an additional 0.2. Our TRECO 
study showed a reduction of 0.3 in BMI-Z values, with an SD of 0.6, after 12 
weeks of the TRE intervention in obese children. Based on these results, we 
assumed that the difference in BMI-Z values between the two groups after 
the intervention would be 0.2 (SD = 0.6). We therefore planned to include 
690 students from six schools in each group, with an average of 115 students 
per school. This was calculated using a two-sided test at a level of 
significance of α = 0.05, with 80% statistical power (1 − β = 0.8), an intra-
group correlation coefficient (ICC) of 0.025, and a 10% loss to follow-up 
rate. 

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Statistical 
Analysis 
This study will be analyzed on an intent-to-order basis. A generalized linear 
mixed-effects model was used to correct for cluster effect, i.e., class and 
school as random effects, for comparison of baseline characteristics of study 
subjects between groups. Subgroup analyses will be used to test for the 
presence of effector modifications. All tests were performed by bilateral test, 
and the P-value <0.05 indicated statistical differences, and all statistical 
analyses were performed using SAS 9.4 statistical software. 
 
2. Background 
With the rapid socio-economic development and the great transformation of residents' 
lifestyles, overweight and obesity are increasingly prevalent in children all over the world, 
particularly in China 1. There are currently nearly 34 million school-age children who are 
overweight or obese in China, accounting for an estimated prevalence of 20% 2. Moreover, 
childhood obesity is an important and modifiable risk factor for cardiovascular and metabolic 
diseases, and about 80% of childhood obesity persists into adulthood, significantly increasing 
the risk of chronic diseases, diabetes, and cardiovascular diseases in particular 3. In addition, 
childhood obesity is highly prevalent between 7 and 12 years, when children spend half of 
their time at school and their behavior is highly malleable. Therefore, prevention and control 
of childhood obesity at school may be one of the main strategies for advancing the window 
of opportunity for chronic disease prevention and control. 
Several studies have confirmed that school-based interventions such as dietary and health 
education programs have a positive effect on the prevention and control of childhood obesity. 
For example, a cluster-randomized controlled trial involving 1,392 school-aged children aged 
8–10 years found that a one-year multidimensional comprehensive intervention (including 
systematic health education, enhanced physical activity programs within schools, and regular 
BMI monitoring with personalized feedback) resulted in a 27.0% reduction in the prevalence 
of obesity in the intervention group. This improvement was significantly greater than the 5.6% 
decrease observed in the control group 4. Similarly, the U.S. “Healthy Schools Program” 
reduced the annual increase in BMI-z scores among students in intervention schools by 0.15 
(95% CI: -0.21 to -0.09) by restricting the supply of sugary beverages 5. A cluster-randomized 
controlled trial in the UK involving 2,000 primary school students found that a one-year 

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“Food Exploration Course” (including cooking practice and interpretation of nutritional labels) 
increased the proportion of intervention group students choosing fruits as snacks from 32% 
to 58%, while the control group only increased by 6% 6, indicating that school-based 
interventions may indirectly influence family dietary decisions through children. Additionally, 
in the Swedish “School Healthy Meals” study, researchers randomly assigned 30 schools to 
an intervention group (providing Mediterranean diet-based meals) and a control group 
(standard meals). After a two-year follow-up, the intervention group's insulin resistance index 
(HOMA-IR) was significantly lower than the control group (1.7 vs. 2.3, P=0.02), validating 
the protective effect of long-term school dietary interventions on metabolic health 7. Overall, 
school-based interventions can effectively optimize students' dietary structure, increase intake 
of healthy foods, and reduce consumption of high-calorie snacks. However, such interventions 
still have limitations, as their effects may be offset by external environments even if they yield 
short-term benefits. An analysis of 27 global studies found that approximately 40% of school-
based intervention effects gradually declined within 2–3 years after the intervention ended 8. 
A French longitudinal study showed that school-based dietary interventions reduced obesity 
rates by 18%, but obesity rates rebounded to baseline levels within two years after students 
entered middle school (outside the intervention environment). As such, the scalability and 
long-term effects of intervention measures are often constrained by implementation 
challenges and insufficient follow-up resources. Some studies indicate that family factors such 
as low parental education levels or occupational types may weaken intervention effectiveness, 
and that translating health knowledge into behavior is particularly challenging. Therefore, 
while school-based dietary intervention strategies hold public health value in theory, their 
practical implementation faces multidimensional barriers that significantly undermine the 
feasibility of such measures. There is an urgent need to introduce more feasible dietary 
behavior training measures to establish and reshape students' healthy eating habits. 
Childhood obesity is largely attributable to an irrational dietary structure, unhealthy 
dietary behaviors, and inappropriate feeding practices during infancy and early childhood. 
Calorie-restricted diet (CRD) represents the primary treatment for childhood obesity 9. 
However, adherence to this dietary regimen is challenging for most children and their families, 
with poor compliance negatively impacting the management of childhood obesity, particularly 
in the long term 10. This underscores the need for the development of more efficacious dietary 
intervention strategies for childhood obesity to provide a broader range of treatment options. 

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Recently, there has been a growing interest in changing dietary patterns, particularly the 
proposal and popularity of intermittent fasting programs, which have demonstrated positive 
effects on metabolic control, weight management, and symptom improvement 11. They are 
also more easily accepted by the public and have higher compliance 12. Intermittent fasting is 
a simple and practical dietary management tool that limits calorie intake during a specific 
period of time. The main types of fasting programs currently in use include alternate-day 
fasting, periodic fasting, and time-restricted eating (TRE). These programs have been shown 
to induce comparable weight loss to that of CRD, with an approximate weight loss of 3-8% 
over a period of 8-12 weeks 13. However, most of these findings are from adults and the 
intervention duration is relatively short. Consequently, the long-term effects of intermittent 
fasting remain inconclusive, and there is currently no evidence of its efficacy in reducing 
weight in children with obesity. 
Two pilot studies have been conducted to examine the feasibility, effectiveness, and 
adherence of intermittent fasting for the treatment of childhood obesity. One single-arm trial 
including 30 obese children aged 12-17 years found that BMI and lipids were reduced and 
vascular endothelial function, healthy eating behaviors, and quality of life were improved 
after intervention 14. The other trial including 50 obese children aged 14-18 years found a 
significant reduction in BMI after 12 weeks of 16-hour TRE compared with the control group 
(no restriction of energy intake). The fasting program was completed 5.3 days per week 
without any adverse effects such as compensatory eating 15. These findings suggest that 
intermittent fasting is feasible and effective for children with obesity. Further, an ongoing 
RCT will compare BMI reductions between CRD and 16-hour TRE after 8 weeks of 
intervention in patients with childhood obesity aged 8-18 years 16. Moreover, in consideration 
of the real circumstances for school-age children in China, e.g., heavy schoolwork, high 
expected body height, and sumptuous dinners with their family, neither alternate-day fasting 
nor periodic fasting may be applicable for Chinese children. TRE only requires control of the 
eating time window and no energy restriction, and thus is simple and easy to implement and 
is expected to be a feasible and compliant dietary intervention for childhood obesity in China. 
However, there is a shortage of evidence from trial studies on adherence and efficacy, 
especially the long-term effect, of TRE in childhood obesity. 
In the TRE program, participants only need to consider two dietary elements: the timing 
of meals and the duration of fasting. As for the first element, the evidence remains 

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inconclusive, but available evidence suggests that the earlier dinner ends, the better. For 
example, a crossover trial study including twenty healthy volunteers confirmed that those who 
ate dinner at 10:00 p.m. had higher blood glucose levels and lower overnight fat burning 
compared to those who ate dinner at 6:00 p.m 17. Another crossover trial study of 18 
overweight or obese individuals also confirmed that those who ate dinner at 9:00 p.m. had 
increased hunger and decreased energy expenditure during the day compared to those who ate 
dinner at 5:00 p.m 18. Regarding the second element, how many hours of fasting is best for 
weight loss is either not clear. Existing TRE-related trials have confirmed that fasting for 12-
16 hours can all produce a weight loss of 2.6-8% 19. Further, an RCT including 60 obese adults 
found that 8 weeks of 12-hour TRE and 14-hour TRE resulted in 6.6% and 7.8% weight loss, 
respectively, with no group differences 20. Another study extended the duration of fasting to 
18 and 20 hours and found only 3.2% weight loss in both groups after 8 weeks of intervention 
21. It can be seen that the duration of fasting is not as long as it should be, and the longer it is, 
the worse compliance may be. Taking into account the available evidence, the optimal 
program for TRE may be to fast for 12-16 hours, with the last meal preferably at 7:00 p.m. 
In summary, the 12-hour TRE may be the healthy dietary behavior pattern we are seeking, 
potentially offering a viable approach to improving the effectiveness of obesity prevention 
and control among children in China. Therefore, this study plans to conduct a school-based 
cluster randomized controlled trial to evaluate the effectiveness of the 12-hour TRE in 
preventing and controlling childhood obesity. We hypothesize that the adoption of the 12-hour 
TRE as a dietary behavior habit may yield better outcomes in preventing and controlling 
childhood obesity compared to current comprehensive interventions based on learning. 

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3. Study Design 
SCHOOL-TRE is a cluster-randomized controlled trial in which 12 primary schools 
(campuses) in Suzhou will be randomly assigned to the intervention (6 schools) and control 
arms (6 schools). At each school, study subjects will be recruited in a class unit, ensuring that 
at least 690 children will be enrolled in each arm. The control group will undergo routine health 
education, and the intervention group will additionally receive a 12-hour TRE training. After 9 
months (1 school year) of intervention, weight management and prevalence of childhood 
obesity will be compared between the two groups. Then the intervention will be stopped, but 
follow-up will be continued, and the sustained effect of the intervention will be evaluated at 1 
year after the intervention (2 school years). The design is illustrated in Figure 1. 
Figure 1. A flowchart illustrating the study design 
4. Objectives 
The primary objective of the SCHOOL-TRE is to evaluate the effectiveness of the 12-h 
TRE on the prevention and management of childhood obesity in school-aged children. In 
addition, the sustained effect of 12-h TRE will be examined at 1 school year after intervention. 
This implementation study will provide trial evidence for the usefulness of 12-h TRE in the 
6 schools assigned to 
the intervention arm 
6 schools assigned to 
the control arm 
Standard health 
education + 12-h TRE 
Standard health 
education 
Follow-up every 
semester 
Primary outcome at 1 
school year 
Primary outcome at 1 
school year 
Stop intervention 
Sustained effect at 2 
school years 
Sustained effect at 2 
school years 
12 schools

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prevention and management of childhood obesity. 
5. Study participants 
This study plans to recruit the fourth-grade students from 12 elementary schools or 
campuses by randomly selecting 3-4 classes in each school/campus. Typically, all students in 
the selected classes will be invited to participate in the study, ensuring at least 115 students will 
be included in each school. 
5.1 Eligibility criteria for schools: 
 The principal agrees to accept the randomization process and adhere to the study 
protocols. 
 The total number of fourth-year students in the school must be more than 50. 
 Schools that have not or plan to implement obesity prevention interventions. 
 Schools that are not boarding schools, ethnic minority schools, or specialty schools. 
 Schools that have no clear plans to relocate or close within the next 2 years. 
5.2 Eligibility criteria for classes: 
 The class head teacher is willing to actively participate in home-school liaison. 
 Class size should be between 30 and 60 students. 
 The class consists of fourth-grade students. 
 There are students with childhood obesity in the class. 
 Classes that have no clear plan to be merged or canceled within the next 2 years. 
5.3 Eligibility criteria for students: 
All students in the class will typically be the subjects of the study after their patients sign 
the informed consent forms, unless they have the following circumstances: 
 Students with a history of heart disease, high blood pressure, diabetes, tuberculosis, 
asthma, hepatitis, or nephritis. 
 Students with secondary obesity due to endocrine disorders or side effects of 
medications. 
 Students with abnormal growth and development, such as dwarfism, gigantism, etc. 
 Students with physical deformities, such as severe scoliosis, chicken breasts, 
claudication, and significant O-leg/X-shaped legs. 
 Students with limited athletic ability who are unable to participate in school physical 
activities. 
 Students who have lost weight by inducing vomiting or taking medication in the past 

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3 months. 
 Students who have undergone prior bariatric surgery. 
 Students with mental disorders, intellectual developmental disabilities, and aphasia. 
 Students who have taken medications that affect appetite or weight within three months 
(e.g., antipsychotics, hypnotics, weight loss medications, insulin). 
 Students who plan to transfer within the next 2 years. 
6. Randomization and recruitment 
In this trial, 12 primary schools or campuses will be randomly assigned to two groups 
using the simple randomization method. The School of Public Health at Suzhou Medical 
College of Soochow University will complete the randomization strategy, and the random 
coding will be generated using the PROC PLAN program in the SAS software. The ratio of the 
experimental group to the control group is 1:1. 
To facilitate the study procedures, we will recruit participants from fourth-grade students, 
with classes as the unit. This approach takes into account the students' comprehension ability 
and the age at which childhood obesity most commonly occurs. This study plans to select a 
Year 4 class (8–10 years old) from each school, comprising 30–60 students per class and a total 
of at least 115 students per school. Once the students' guardians have been fully informed of 
the research protocol and have signed the informed consent form, the study subjects will be 
provided with a free health assessment to determine whether they meet the inclusion criteria. 
All eligible students will then be included in the study. 
7. Interventions 
7.1 Interventions for the control group: 
Standard health education procedures are in place. Health education will be conducted in 
accordance with the "Guiding Outline for Health Education in Primary and Secondary 
Schools." 
7.2 Interventions for the experimental group: 
In addition to the standard health education procedures, subjects in the experimental group 
will undergo 12 hours of TRE training. The core content of the propaganda and education on 
the 12-hour TRE feeding model is that the eating time window is limited to 12 hours per day, 
and the last meal must be finished by 19:00. The study subjects can freely choose their eating 
time window and are not restricted in terms of energy intake during mealtimes. During the 

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fasting period, they are allowed to drink non-calorie, sugar-free beverages such as water, tea, 
and coffee. The time of eating should be recorded every day. 
8. Data collection 
Data collection at the screening, baseline, and follow-up visits will be conducted by trained 
and qualified staff. The schedule of data collection is outlined in Table 1. At each visit, data on 
sociodemographic, behaviors, and disease history of individuals and families will be collected 
through questionnaires and clinical examinations. Data on adverse events will be actively 
monitored during follow-up. The specific data collection and the corresponding procedures are 
detailed below: 
Table 1. The schedule of data collection 
Data collection 
Baseline visit
Intervention 
Follow-up 
4 months 
9 months 
21 months 
Informed consent 
× 
 
 
 
General characteristics 
× 
 
 
 
Anthropometry 
× 
× 
× 
× 
Blood pressure 
× 
× 
× 
× 
Physical activity 
× 
 
× 
× 
Diet behavior 
× 
 
× 
× 
Quality of life 
× 
 
× 
× 
Adverse events 
× 
× 
× 
 
8.1 Questionnaire survey 
 Demographic information: Age, gender, student ID, national ID number. 
 Socioeconomic factors: parental education level, household income. 
 Fetal development: gestational age at birth, birth weight, mode of delivery, and 
feeding method. 
 Personal medical history: diabetes, constipation, OSAS, bariatric surgery, 
antipsychotics, hypnotics, weight-loss medications, insulin, etc. 
 Family history of disease: obesity, hypertension, diabetes. 
 Lifestyle: physical activity, dietary habits, sedentary time. 
 Psychological factors: quality of life. 
 Adverse events: dizziness, fatigue, etc. 

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8.2 Clinical examination 
Body weight and height, waist circumference, hip circumference, and upper arm 
circumference will be measured by standard methods. Blood pressure will be measured three 
times at each visit. The average of the three readings constitutes the blood pressure value for 
that measurement. 
9. Methods of data measurement 
9.1 Questionnaire survey 
 
A face-to-face survey is conducted by a trained and qualified investigator with each 
participant, using a standardized, self-administered questionnaire to collect demographic 
information (age, sex), fetal development (gestational week of birth, birth weight, delivery, 
feeding), and personal and family history of disease (obesity, hypertension, diabetes). 
Standardized scales are used to assess the lifestyle (physical activity, eating behaviors), and 
quality of life of the study subjects. Specifically, the Physical Activity Questionnaire for 
Adolescents (PAQ–A), a self-report scale designed for use with school students, will be used to 
assess the physical activity in our study. It contains eight items intended to capture adolescents' 
recollections of their physical activity over the preceding 7 days. The first and last of the PAQ–
A's eight items each contain a number of subitems from which a mean is initially calculated, 
and those two means are added to responses on the other six items to obtain a total from which 
the mean is calculated to produce a composite score ranging from 1 to 5, with higher scores 
indicating greater physical activity. A ninth question seeks information about anything that 
would have prevented respondents from engaging in their “normal physical activities” during 
the previous week. The Child Eating Behavior Questionnaire (CEBQ), designed to assess 
children’s eating scale styles, will be used in our study. It is a parent-report measure comprised 
of 35 items, each rated on a five-point Likert scale that ranges from never to always. It is made 
up of eight scales: Food responsiveness, Emotional over-eating, Enjoyment of food, Desire to 
drink, Satiety responsiveness, Slowness in eating, Emotional under-eating, and Food fussiness. 
The instrument is ideal for use in research investigating the early precursors of eating disorders 
or obesity. The Quality of Life Scale for Children and Adolescents (QLSCA) is a Chinese 
version of the quality of life Scale for Children and Adolescents, consisting of 49 items for 
measuring 13 dimensions of students’ lives, such as their relationships with teachers and parents, 
partnership with fellow students, learning abilities and attitudes, self-perception, physical well-
being, negative emotions, attitudes towards homework, living environment convenience, social 

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activities, sports capacity, self-satisfaction, and other unspecified factors. The QLSCA uses a 
five-point Likert-type scale to measure either frequency or intensity, with a recall period of two 
weeks. Scores were calculated for each dimension, with higher scores indicating a better quality 
of life. 
9.2 Anthropometry 
Body weight and height were measured using a regularly calibrated stadiometer and 
balance-beam scale with participants wearing light clothing and no shoes. Body mass index 
(BMI) was calculated as weight in kilograms divided by height in meters squared. The BMI-Z 
score was calculated based on the WHO growth charts. Waist circumference was measured at 
1 cm above the umbilicus. Hip circumference is measured by taking a tape measure and 
wrapping it around the widest part of the hips, which is typically around the buttocks. Arm 
circumference was measured at the midpoint between the acromion and the olecranon of the 
right arm. 
9.3 Blood pressure 
Three consecutive sitting blood pressure measurements (with 30 sec in-between) were 
taken by trained staff using a digital blood pressure measuring device (HBP-1320, Omron, 
Japan), after the subjects had been resting for at least 5 min. All participants were required to 
avoid exercise, smoking, drinking alcohol, and tea for at least 30 min before the measurement. 
10.  Outcomes 
 
This study is designed to test both long-term and sustained effectiveness of 12-h TRE on 
obesity management, with the long-term outcome being the magnitude of weight loss after 9 
months (one academic year) of intervention. The intervention was then stopped but follow-up 
was extended to 21 months (one academic year after intervention) to assess the sustained effects, 
with the same outcome events as the long-term outcome. 
Primary outcome： 
Change in BMI-Z score 
Secondary outcome： 
 
Change in BMI 
 
Change in the prevalence of childhood overweight or obesity (BMI-Z>2) 
 
Change in blood pressure  
 
Change in waist-to-hip ratio 
 
Change in quality of life 

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 
Change in eating behavior 
 
Change in physical activity 
11.  Assessment of Outcomes 
In this study, outcomes are assessed using standardized, internationally accepted measures. 
Blindness (the follow-up assessors are unaware of the grouping of study subjects) is used in the 
outcome assessment process. 
12.  Statistical Power and Sample Size 
The DECIDE-Children study demonstrated that a comprehensive school-based 
intervention reduced BMI-Z values by an additional 0.2. Our TRECO study showed a reduction 
of 0.3 in BMI-Z values, with an SD of 0.6, after 12 weeks of the TRE intervention in obese 
children. Based on these results, we assumed that the difference in BMI-Z values between the 
two groups after the intervention would be 0.2 (SD = 0.6). We therefore planned to include 690 
students from six schools in each group, with an average of 115 students per school. This was 
calculated using a two-sided test at a level of significance of α = 0.05, with 80% statistical 
power (1 − β = 0.8), an intra-group correlation coefficient (ICC) of 0.025, and a 10% loss to 
follow-up rate. 
13. Data management 
All data are entered into the electronic database in the School of Public Health, Suzhou 
Medical College of Soochow University by trained and qualified nurses or investigators using 
an epidemic survey system (https://edc.gwxy.suda.edu.cn). The data entered are reviewed for a 
final data check and quality control. 
14.  Statistical analysis plan 
This study will be analyzed on an intent-to-treat basis. A generalized linear mixed-effects 
model was used to correct for cluster effect, i.e., class and school as random effects, for 
comparison of baseline characteristics of study subjects between groups. Subgroup analyses 
will be used to test for the presence of effector modifications. All tests were performed by 
bilateral test, and the P-value <0.05 indicated statistical differences, and all statistical analyses 
were performed using SAS 9.4 statistical software. 
15.  Quality control 
 
Quality control will be conducted by a team of investigators, key research staff, and project 
inspectors. Strict quality control will be implemented at every step of the study including project 
preparation, training, screening, intervention, and data collection. A manual of procedures will 

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17 
 
be developed to detail the standardized approaches used in the study, such as participant 
recruitment, intervention, doctor training (protocol-based treatment, health coaching, and 
follow-up), health education (self-diet monitoring methods, lifestyle changes, and medication 
adherence), and other procedures of the study. All study personnel will be required to participate 
in a study training session prior to the initiation of any study procedures. The quality control 
team will review the study data regularly to ensure that all phases of the project are strictly 
implemented according to the study protocol and the authenticity, completeness, accuracy, and 
reliability of the research data. 
15.1 Preparation phase 
 
A manual of procedures will include detailed descriptions of all trial procedures and will 
be used for training purposes and as a reference for all study investigators and staff. Standard 
forms, devices, and procedures in the field for energy intake diary and other data collection 
procedures will be standardized. Furthermore, standard event definitions and event validation 
procedures will be used. The project will purchase the devices used in the study which pass the 
national quality inspection and provide these to local research teams. We will calibrate each 
device before they are distributed to study sites. The study protocol, manual of procedures, 
study forms, training materials, and other written materials will be prepared centrally. 
15.2 Screening and recruitment phase 
 To carry out obesity-related health education for children and their families, to ensure 
that they fully understand the hazards of childhood obesity, to establish confidence that 
obesity is preventable and controllable, and to try to include all eligible children. 
 The enrolled children are trained to ensure that they are able to complete and upload a 
diet time diary and a weekly physical activity diary. 
15.3 Implementation stage 
 Dedicated participants are responsible for the collection of diet diaries and weekly 
physical activity diaries, and quality control participants assess the completion of the 
interventions and provided timely feedback to the attending physician in order to 
facilitate his or her supervision of the completion of the medical prescriptions. 
 Dedicated follow-up appointments to reduce missed appointments. 
 Follow-up outcomes are assessed by applying a blinded method (the assessor is unaware 
of the grouping of study subjects). 

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16.  Security monitoring 
16.1 Adverse events and reports 
The intervention program in this study is more feasible. Possible adverse events include 
compensatory eating and reduced physical activity, which have been monitored at follow-up, 
and other adverse events not listed are reported and registered by the study subjects and their 
families with the nutritional counsellor. 
16.2 Data security 
After reviewing and confirming that the database created is correct, the data are locked by 
the principal investigator, the sponsor, and the statistical analyst. No further changes are made 
to the data files after locking. Problems identified after data locking should be followed strictly 
by the process of unlocking and re-locking the data. The Data Safety Committee and Ethics 
Committee are responsible for monitoring. 
17.  Study organization 
SCHOOL-TRE is conducted jointly by the School of Public Health, Medical College of 
Soochow University, the Children's Hospital of Soochow University, and Wujiang Children’s 
Hospital, forming a multidisciplinary and multi-departmental collaborative team of researchers 
(Figure 3). Decision-making, protocol design, overall organization, management and 
coordination of the study are carried out by the study steering committee, screening, recruitment 
and intervention management of the study subjects are implemented by the intervention team, 
blinded assessment of the outcome is implemented by the follow-up team, data quality control 
is implemented by the quality control team, and statistical analysis and reporting of the results 
is carried out by the Data Analysis Centre. Statistical analysis and reporting of results are carried 
out by the Data Analysis Centre, and the Data Safety Management Committee supervised the 
entire implementation of the project. Adopting a management model of overall coordination 
and division of labor and responsibility, and implementing a job responsibility system. 

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Figure 2. Study Organization Structure 
18.  Ethnic consideration 
It is the responsibility of the principal investigator to ensure that this trial will be conducted 
in full compliance with the Declaration of Helsinki and the Chinese Code for Quality 
Management of Clinical Trials, as well as other relevant regulations. The study protocol was 
reviewed by the Ethics Committee of Soochow University and the Ethics Committee of 
Affiliated Children's Hospital of Soochow University, and all study subjects and their guardians 
signed an informed consent form. 
19.  Schedule 
SCHOOL-TRE will last for two years and the schedule is shown in Table 2. 
Table 2. Timeline and workplan 
Research tasks 
2025 
2026 
2027 
5-
6 
7-
8 
9-
10 
11-
12 
1-
2 
3-
6 
7-
8 
9-
12 
1-
8 
9-
10 
11-
12 
registration, research tools 
  
  
  
  
  
  
  
  
  
  
 
Development of workbooks 
  
  
  
  
  
  
  
  
  
  
 
Preparations, training 
  
  
  
  
  
  
  
  
  
  
 
Recruitment of study 
participants, baseline data 
collection 
  
  
  
  
  
  
  
  
  
  
 
Interventions and quality 
  
  
  
  
  
  
  
  
  
  
 
Steering committee 
Follow-up team 
(Wujiang Children’s 
Hospital) 
Quality control team 
(Wujiang CDC) 
Data Safety Management 
Committee 
Data analytical center 
(Soochow University) 
Intervention team 
(Children’s Hospital of 
Soochow University) 

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control 
Follow-up 
 
 
 
 
 
 
 
 
 
 
 
Data analysis,  
writing papers 
  
  
  
  
  
  
  
  
  
  
 
20.  References 
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Bjerregaard LG and Baker JL. Change in Overweight from Childhood to Early Adulthood and Risk of Type 2 
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Serra-Majem L, Roman B and Estruch R. Scientific evidence of interventions using the Mediterranean diet: 
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