Determine the BMI levels, self-concept and healthy life behaviours of children during a school based obesity training programme.

Sedentary lifestyles and unhealthy nutrition, in particular, cause childhood obesity. The purpose of this semi-experimental research is to determine the changes in body mass index, self-concept, and healthy lifestyle behaviours of children during a training programme to prevent obesity. Children 9 and 15 years old were included from two public secondary schools. A total of 1609 students completed the study in the intervention and control groups (1022 vs 587, respectively). The training programme for the intervention group at the schools had three sessions in 12 weeks and was about obesity, body mass index (BMI) calculation, a healthy lifestyle and coping with stress. Data was collected through a sociodemographic data form, healthy lifestyle behaviours data form, Piers-Harris Children's Self-Concept Scale and weight-height measurements during the first and last weeks of the programme (except for the sociodemographic form). Before training, BMI's of children in the intervention group were higher than in the control group (19.61 ± 3.8 vs 19.00 ± 3.5, respectively). The gap between BMI scores of the groups was narrowed after the training (p > 0.05). The mean score on the Self-Concept Scale increased in the intervention group after the training (63.21 ± 9.5) as compared to before the training (61.16 ± 10.4); whereas in the control group, there were no differences found (p = 0.908). In the intervention group, the number of children who had breakfast after the training (81.1%) increased compared to before the training (74.1%) (p = 0.001). The trainings were provided to students to increase healthy nutrition, physical activity and to decrease sedentary lifestyles.