This study aims to evaluate the effects of a school-based nutrition education program and the implementation of a school dietitian model on primary school students in Mardin, Türkiye. A total of 67 fourth-grade students were randomized into intervention (n=32) and control (n=35) groups. The intervention group received an eight-week classroom-based nutrition education program, while their parents received four weeks of parent-focused education. Outcomes were measured using the Nutrition Knowledge Test, Nutrition Attitude Scale, Nutrition Behavior Scale, Child Physical Activity Questionnaire, and anthropometric assessments including weight, height, BMI, and waist circumference. The study seeks to determine whether dietitian-led school-based nutrition education can improve children's nutrition knowledge, attitudes, and behaviours, as well as influence anthropometric measures. Findings from this trial are expected to inform future strategies for integrating school dietitians and structured nutrition education into primary schools in Türkiye.

Childhood obesity and malnutrition are urgent public health challenges in Türkiye, particularly in regions with limited access to structured health promotion programmes. Schools represent an appropriate setting for preventive strategies as they provide consistent opportunities for health education and behaviour reinforcement.

Study Design and Randomisation This study was designed as a single-centre, parallel-group, randomised controlled trial (RCT) conducted in a public primary school in Mardin, Türkiye. A total of 70 fourth-grade students were recruited and randomly allocated into intervention and control groups using a simple randomisation procedure performed by an independent researcher. Allocation was concealed until group assignments were finalised.

Intervention The intervention group participated in an eight-week school-based nutrition education programme, led by a registered dietitian, with one session delivered per week during school hours. Each session lasted approximately 40 minutes and included structured modules on food groups, balanced diet, healthy snacking, and the risks of processed foods. Interactive teaching methods such as educational games, puzzles, and visual aids were applied to increase engagement. In parallel, parents of the intervention group students attended a four-week supplementary programme delivered in evening sessions, covering home-based nutrition practices and strategies for supporting healthy child eating behaviours.

The control group continued routine school activities during the study period. To ensure equity, they were provided with an abridged version of the nutrition education materials after study completion.

Data Collection Procedures Measurements were performed at three time points: baseline (T0), immediately after the intervention (T1), and two months post-intervention (T2). Trained assessors, blinded to group allocation, collected data following standardised protocols.

Instruments used included:

• Nutrition Knowledge Test (NKT)
• Nutrition Attitude Scale (NAS)
• Nutrition Behaviour Scale (NBS)
• Child Physical Activity Questionnaire (CPAQ)

Anthropometric data (height, weight, waist circumference, and BMI) were measured using calibrated equipment under uniform conditions.

Outcomes and Analysis Primary outcomes included changes in nutrition knowledge, attitudes, and behaviours, as well as physical activity levels. Secondary outcomes focused on anthropometric indicators and dietary habits. Data were analysed using intention-to-treat principles. Continuous variables were evaluated with repeated measures ANOVA to detect changes across the three assessment points, while categorical variables were tested with chi-square statistics. A p-value <0.05 was considered statistically significant.

Ethical and Quality Considerations Ethical approval was obtained from the institutional review board, and written informed consent was secured from parents alongside child assent. Confidentiality was maintained by anonymising data, and all educational materials were standardised to ensure consistency in intervention delivery.

Significance By providing a structured description of the intervention design and evaluation process, this study aims to generate evidence for the effectiveness of integrating school dietitians into the Turkish primary education system. The results will inform national strategies targeting childhood obesity prevention and promote sustainable health policies.

Inclusion Criteria:

• Enrolled as a fourth-grade student in the selected primary school in Mardin, Türkiye.
• Aged between 10 and 11 years.
• Able to participate in classroom-based activities and complete the study assessments.
• Obtained written informed consent from parents.

Exclusion Criteria:

• Students with physical or cognitive impairments that prevent participation in educational sessions or completion of questionnaires.
• Absence from school during the intervention period that would preclude participation in the majority of sessions.

Individual participant data (IPD) will not be shared due to privacy concerns and ethical considerations related to the small sample size, which may increase the risk of participant identification

The study was conducted as a single-blind trial. Participants and intervention providers were aware of group assignments; however, the researcher responsible for outcome assessments and data analysis was blinded to group allocation to minimize bias.