Background: Strategies to treat and prevent obesity are urgently required in Malaysia, and it is now considered a public health priority. Aims: The present study aims to evaluate the effectiveness of the i-MaCHeL intervention for preschool's child-parent dyads. The primary objective of the present study is to compare the changes in the child BMI-for-age z-score at 3- and 9-month after baseline measurement. The secondary objectives of the present study are to compare the changes in child dietary intake, child physical activity, child health-related quality of life, parental self-efficacy, parental role modeling, and parental policies at 3- and 9-month after baseline measurement. Study design: The i-MaCHeL intervention is a single-blind, two-group cluster-randomized controlled trial that evaluates the effectiveness of a 3-month obesity prevention intervention on preschool's child-parent dyads at 3- and 9-month after baseline. The participating preschools (n=12) will be randomized to either the intervention or control group in a 1:1 ratio. The present study will involve 460 child-parent dyads of preschool children aged 5 and 6 years old and their parents in Terengganu, Malaysia. Briefly, the preschool children in the experimental group will be received the i-MaCHeL program delivered through interactive classroom instruction, and their parents will have access to the i-MaCHeL Web-based program. In the control group, the preschool children will be received a standard preschool health education curriculum, and their parents will have access to the general Web-based health newsletters. Instruments: Anthropometric measurements (body weight and height) will be assessed according to the WHO standard procedures. Dietary intake of children will be measured using dietary records for three days. Child physical activity, child health-related quality of life, parental role modeling, parental policies, and parental self-efficacy will be assessed using previously validated parent-proxy questionnaires. Conclusion: The strategies to promote healthy eating in reducing the prevalence of obesity among Malaysian preschool children may have long-term benefits to children's health. The combinations of the two modes of delivery (interactive classroom instruction for preschool children and a Web-based program for parents) will have a strong potential to be effective strategies to sustain child-parent engagement and participation in the health-related behavior change program.

1. Research Hypotheses

   The primary hypothesis of the present study is that the preschool children in the i-MaCHeL intervention group would achieve a significant improvement in BMI z-score compared with those in the comparison group at 3- and 9-month after baseline measurement.

   The secondary hypotheses of the present study, as stated below:

   1. Preschool children in the i-MaCHeL intervention group would achieve significant improvements in dietary intake, physical activity, and health-related quality of life compared with those in the comparison group at 3- and 9-month after baseline measurement.
   2. Parents of preschool children in the i-MaCHeL intervention group would achieve significant improvements in parental self-efficacy, parental role modeling, and parental policies compared with those in the comparison group at 3- and 9-month after baseline measurement.

2. Study Location

   Two districts, which are Kuala Terengganu and Kuala Nerus, will be included in this study. These two districts are chosen based on demographic and logistic factors as it is within 35 miles (56 kilometers) of the study center.

3. Reference Population

   The reference population will be based on a sample population drawn from the MOE public preschools in the Terengganu that are registered at the Ministry of Education Malaysia (MOE). There are 307 MOE public preschools with a total of 11,600 children in Terengganu. All children attending MOE public preschool in the Kuala Terengganu and Kuala Nerus districts will be included as the reference population in the present study.

4. Source Population

   The primary sample consists of 5- and 6-year-olds children (born in the year of 2016 and 2017) that attending MOE public preschools, and their parents, living in the Kuala Terengganu and Kuala Nerus districts. There are 71 MOE public preschools in Kuala Terengganu (n=45 preschools) and Kuala Nerus (n=26 preschools), with a total of 1,850 and 1,175 children, respectively.

5. Study Participants

   The preschool's child-parent dyads that fulfill the selection criteria of the present study will be eligible for inclusion. In total, 12 preschools with 460 child-parent dyads will be recruited.

6. Sample Size Determination

   The present study is a preschool-based cluster-randomized controlled trial that evaluates the effectiveness of a 3-month obesity prevention intervention in preschool's child-parent dyads. Twelve preschools with approximately 38 child-parent dyads per preschool, will be enrolled in the present study at baseline. With at least 90% power to identify a small to medium effect size at the 5% significance level, the present study needs a sample of size 460 child-parent dyads. The intervention and control group will each have 230 child-parent dyads in the sample.

7. Sampling Frame

   All preschools located in the Kuala Terengganu and Kuala Nerus districts (n=71), with a total of 3,025 children, will be assessed for inclusion. The preschools with fewer than 38 children (minimum cluster size) or preschools with "special measures" (unlikely to have the capacity to contribute to the study) will be excluded from the study. After the inclusion and exclusion criteria screening, a list of 37 preschools (n= 1,850 children) will be expected to be eligible and invited to participate in the present study. From the list, only 12 preschools will be recruited in the study. The list of all children attending the included preschools will be obtained from the preschool teachers.

8. Sampling Method

   A cluster random sampling technique (probability sampling) at the preschool level will be conducted in the present study. Thirty-seven preschools (expected to be eligible) will be randomly ordered using a random number generator to generate a list of random numbers, and sequentially will be invited to participate. All the preschools will be contacted, and 12 of them will be recruited in the study.

9. Randomization

   Notably, the randomization into intervention and control groups will only occur at the preschool level. Thus, randomization will be carried out at the preschool level rather than the child participants level to minimize the possibility of the experimental group participants would influence by the participants in the control group. In total, 12 preschools, 6 per arm, will be randomized into either the experimental or control group in a 1:1 ratio. After the baseline measures are completed, the participating preschools will be randomized at the start of the preschool year using a randomization computer program of Research Randomizer (version 4.0). The data analyst who randomized the preschools has no contact with the principal researcher, preschool personnel, or study participants.

10. Overview of the Interactive Malaysian Childhood Healthy Lifestyle Program (i-MaCHeL) intervention

    The i-MaCHeL intervention is designed in an innovative approach to delivering a health-related behavior change program among preschool's child-parent dyads to prevent childhood obesity. The i-MaCHeL intervention encourages children to practice a healthy lifestyle and educate parents to shape home lifestyles for optimal child growth and development. Furthermore, the i-MaCHeL intervention is unique, given its Web-based approach to enhance the tool's adoption with hard-to-reach populations, contributing to the long-term goal for childhood obesity prevention. The combinations of the two modes of delivery (interactive classroom instruction for preschool children and a Web-based program for parents) will have a strong potential to be effective strategies to sustain child-parent engagement and participation in the health-related behavior change program.

    In recognition of the value of multiple theoretical approaches, the strong theoretical basis consists of Social Cognitive Theory (SCT), Health Belief Model (HBM), and Trans-Theoretical Model (TTM) principles will be underpinning the development of the i-MaCHeL intervention. These theories' concepts and principles will be ensured to well suited with the i-MaCHeL in supporting desired healthy lifestyle behaviors and healthier weight outcomes. The main contents of the i-MaCHeL program are healthy eating, active physical activity (moderate-intensity exercise), and sedentary behavior (sleep and screen time), which are based on evidence-based national recommendations for a healthy lifestyle targeting preschool children. Educational and behavior change materials of a healthy lifestyle will be developed by following the guidelines from the Malaysian Dietary Guidelines for Children and Adolescents.

11. Intended Statistical Analysis

Differences in changes over time between the intervention and comparison groups will be assessed for each outcome. General linear model repeated measure analysis will be used to determine differences between groups over time (baseline, 3-month, and 9-month) with adjustment for potential covariates. Intention-to-treat (ITT) principles will be applied for parametric data, with all participants analyzed in both intervention and control groups regardless of whether they attended all data collection time points or completed the intervention. Descriptive statistics will be calculated to describe participants' sociodemographic characteristics and scores for each outcome measure by treatment and control groups at baseline, 3-month, and 9-month. Repeated measures analysis of variance (ANOVA) will be conducted to identify significant differences within-group at 3- and 9-month surveys. Whereas repeated measures Analysis of Covariance (ANCOVA) will be performed to determine significant differences between-group at the 3- and 12-month surveys. The measures analyses will be controlled for covariate variables known to influence the outcome measures (child gender, parent education level, parent aged, and parent income). The significance level will be set at < 0.05. Analyses will be performed using Statistical Package for the Social Science (SPSS; version 25.0).

Inclusion Criteria:

To be included in the study, children have to be aged 5- or 6-years Malaysian citizens and attending MOE public preschools in the Kuala Terengganu and Kuala Nerus districts. Besides, the parent/guardian of the preschool children must:

• Could read and understand either English or Malay
• To be aged between 25 to 49 years
• Have regular internet access via a tablet device, mobile phone, or computer/laptop
• Have regular access to a phone with texting capability
• Have WhatsApp and Facebook accounts or agreed to create the accounts
• Comfortable to read/view materials on electronic devices
• Willing to complete all questionnaires with their child throughout the study

Exclusion Criteria:

Child-parent dyads will be excluded if they have the following criteria:

• Children that are taking medications or have a medical condition with the potential to affect the weight or restrict age-appropriate play
• Children that are having conditions that require the restriction of certain foods (e.g., celiac disease or food allergies)
• Parents that are suffering from a severe physical or psychological illness, making the study too demanding for the family

The single-blind RCT will be applied in the present study, in which the researcher but not the study participants know which intervention has been allocated at the preschool level. In the experimental group, the preschool children will be received the i-MaCHeL program delivers through interactive classroom instruction, and their parents will have access to the i-MaCHeL Web-based program. Whereas in the control group, the preschool children will be received a standard preschool health education curriculum, and their parents will have access to the general Web-based health newsletters.