The prevalence of obesity in children is increasing rapidly, Among children aged 5-12 years, 18.8% have severe overweight, comprising 10.8% who are obese and 8.8% who are over. The development of effective and sustainable intervention strategies to prevent childhood obesity in Indonesia is becoming increasingly important, particularly given the limited implementation of health-promoting schools in the country.

The first Phase using qualitative exploration was a needs assessment will be using of social cognitive theory. The second Phase will be the development model intervention modification of the health promotion school WHO and "Health School". The third Phase is the quantitative stage using a Cluster Randomised Controlled Trial to analyse differences and test the effectiveness of the HPS model. This study will be conducted in 8 primary schools located in Makassar, South Sulawesi. School in Makassar city and schools from outside Makassar city, randomly selected for the trial. Then the selected schools are randomly divided into school for nutrition education and physical activity. Intervention, while school each for comprehensive intervention. The study will be target students in Grades 4 and 5 of primary school. Assessments for the primary objective (BMI Z score), and secondary objectives (change in knowledge, self-efficacy, and health literacy) in thirds study arm. The subsequent phase will assess the efficacy of the intervention in terms of reductions in BMI Z scores, improvements in knowledge, self-efficacy and health literacy. Concurrently, the exploration of parental and teacher knowledge and insights regarding health promotion in schools and its potential in reducing overweight and obesity in children will be conducted.

This research is an exploratory sequential mixed method design. By combining two elements of qualitative and quantitative research approaches. Exploratory sequential mixed method. The qualitative phase includes an exploration of needs assessment with a social cognitive theory approach, the second phase implements the Health Promoting School model for three months. The third phase was quantitative using Cluster Randomised Controlled Trial design. To analyse the effectiveness of a 6-month school-based intervention in children aged 9 and 12 years in schools with A and B accreditation standards. Three interventions will be implemented and outcomes will be measured simultaneously. Sampling in the study, using two steps in the selection of subjects, first 8 schools from the city of Makassar and 4 schools outside the city of Makassar from each school were randomly selected for the trial. then the selected schools were randomly divided into 4 groups, for nutrition education and physical activity interventions, while 4 groups each for comprehensive interventions. Inclusion criteria for selecting schools: 1) non- boarding schools; 2) the prevalence of obesity, based on routine physical examination records, was above 10%; 3) school lunch was provided, and more than 50% of students ate school lunch. All students in the selected classes were invited to participate in the study.

Exclusion criteria for subjects: 1) students suffering from serious diseases (such as congenital heart disease, or other diseases and so on) or unable to withstand strenuous physical activity or dietary regulation were excluded. 2) Students participating in the study or intending to transfer to another similar school in the following year are excluded.

This study will be conducted in Makassar, Gowa and Maros cities in South Sulawesi. The unit of analysis for this study is primary schools, especially in Makassar and other cities. A preliminary study was conducted at all school sites to determine the number of students who would fit the special criteria of 9-12 years of age in primary school children at eight schools in South Sulawesi who were willing to participate in the study. There were eight schools in this study that met these criteria SDN Athira, SD Al-Ashar, SDN Pallangga Gowa, SD Sudirman, SD Alfityan, SDN Tete Batu 1 SDN Tete Batu, and SDN Bulurokeng. The results of the preliminary study showed that the number of overweight and obese students at SDN Athira was 39.4%, SDN Pallangga 27.5%, SD Sudirmana I 45.5%, SD Tete Batu 49.7%, SD Alashar 26.2%, and SD Alfityan 58.7%, SDN Tete Batu I 50.8%, and SDN Bulurokeng 45.7%. Furthermore, from these eight primary schools, the primary schools that will be given the intervention and their willingness to continue their participation in the intervention and implementation of the HPS model for reducing overweight and obesity in primary school children were selected. Based on these criteria, these are the primary schools that will be treated.

Student recruitment: all grade 4 and 5 students who met the inclusion criteria were verbally informed about the study at the time of recruitment. Written information will be given to parents or guardians for them to study and ask them to give informed consent if they agree to their child taking part in the study. Recruitment of UKS teachers, science and sports teachers, or homeroom teachers: with permission from the principals of primary schools willing to participate in the study.

The sample size in this study was determined based on the formula for hypothesis testing of mean differences between intervention. The calculation uses the formula as follows :

All data were presented as mean (SD) or median, range, or percentage (for categorical variations). Statistics analyzed will be used software SPSS and STATA. The normality test used the Shapiro-Wilk test. At baseline measurement, anova test was performed to determine the difference between effectivites. After follow-up, within-group were compared by independent t-test. Comparison of before and after variables was assessed wiil be paired t- test for normally distributed data, or by Mann-Whitney test for non-normally distributed data was considered statistic significant if the P- value of less thsn 0.05 will be considered statiscally. Effect size will be measured using Cohen d. To see the comparison of outcomes measured in months two, four and six will be tested using repeated annova. Analysis of covariance (ANCOVA) was used to test the outcomes that have an effect on the effectiveness of the HPS model and nutrition education and physical activity interventions in overweight and obese children.

Analysis qualitatif with transcripts from all focus groups will be independently analysed by two researchers will be using thematic analysis. The thematic analysis will consist of a six-step approach which includes; (i) data familiarisation achieved by reading each transcript, (ii) initial code generation, (iii) theme search from initial codes, (iv) thematic map generation, (v) specific definition and naming of themes and (vi) final analysis. The two sets of thematic analyses will be compared before the final iteration of thematic analysis is conducted and final themes are generated and consensus is reached. Qualitative data contextual the results and investigates participants, perceptions and attitudes towards the intervention Data collection is done by giving pretest and posttest questionnaires to all children in the intervention group. At the time of data collection, students will be divided into groups. Each group of five students will be guided by an interviewer or facilitator when completing the questionnaire. Each student had to answer all the questions on the questionnaire on the same day. The head of the class emphasised to the students to fill in the questionnaire honestly and that the result of the questionnaire would not affect their rapport score. This is to obtain accurate data. In addition to filling out the questionnaire, anthropometric measurements were also taken on students by trained enumerators. These measurements will be taken on different days during designated hours and will be taken monthly for six months, in all groups.

Inclusion Criteria:

• Male and female gender
• Children aged 9-12 years old (at the time of baseline data collection)
• All fourth and fifth grade students/children
• Children who are willing as respondents and ready to follow the intervention until completion and willing to fill in the informed consent.
• Withdrawal: Children experiencing physical and mental health conditions during the intervention (arising due to the child's own health conditions, not due to the effects of the intervention)
• Full day children

Exclusion Criteria:

• Children with clinical conditions / health disorders such as heart disease etc.)
• Children who did not take the pretest
• Children who left or moved schools
• Children who did not complete the intervention