Health Education Journal, cilt.84, sa.5, ss.516-529, 2025 (SSCI)
Objective: Children’s lifestyle behaviours significantly affect childhood obesity. The impact of a body mass index reduction intervention applied to secondary school students on their eating behaviour, physical activity, sleep quality and obesity was in the focus of this research. Method: A quasi-experimental pre–post design was employed. The research was conducted with sixth-grade students (age 10) studying at two public schools in a province in the east of Türkiye, selected by simple random sampling. The research was carried out with 155 students (n = 84 experimental and n = 71 controls). A body mass index reduction education programme was provided to the intervention group. The training consisted of six modules, each module delivered in one or two sessions lasting an average of 40 minutes. Data were collected using a Socio-Demographic Data Form, CTFEQ, PAQ-C and SQS. The statistical analysis of the data was conducted using IBM SPSS Statistics 24.0. Results: The post-intervention body mass index values of the students in the intervention and control groups did not differ statistically significantly (p > 0.05). Students’ mean scores on the total eating behaviour scale differed statistically significantly for group and group*time interaction (p < 0.05). In addition, the mean physical activity questionnaire and sleep quality scale scores differed statistically significantly in terms of group, time and group*time interaction (p < 0.05). Results showed that the effect size was large for all variables according to the time*group interaction. Conclusion: The results of this study show that education on obesity was not effective in reducing body mass index values. However, it effectively increased students’ mean physical activity, sleep quality scores and positive eating behaviours.