To describe the relationships between physical activity, lifestyle determinants and obesity in adolescent Israeli schoolchildren.

Cross-sectional survey.

The MABAT Youth Survey was a nationally representative, school-based study of youth in grades 7 to 12 (ages 11–19 years).

Self-administered questionnaires assessed health behaviours and anthropometric indices were measured. Logistic regression analysis was used to examine the associations between obesity, physical activity, socio-economic status and other lifestyle habits. One-way ANOVA was used to determine mean physical activity levels (MET values) by BMI categories.

The prevalence of overweight was 13–15 % and of obesity 4–9 % depending on gender and ethnicity, and was higher among the non-Jewish sectors. Thirty-six per cent and 57 % of Jewish girls and boys, and 40 % and 58 % of non-Jewish girls and boys, respectively, were optimally active. Boys from low socio-economic schools and those who slept for less than 6 h at night were less active. Girls from middle school were found to be 53 % more optimally physically active among Jews, and 89 % more among non-Jews, compared with girls from high school (P = 0·001); girls with less educated parents were also less physically active. No clear relationship was found between the level of obesity and physical activity.

Physical inactivity was strongly related to gender, age, social status, sleeping habits, hookah smoking, and parental educational status. Education and intervention programmes should focus on these risk factors.