What factors are associated with excess body weight in Australian secondary school students?

To examine the prevalence of overweight and obesity in Australian secondary school students and identify factors associated with excess adiposity.

Cross-sectional survey of students aged 12-17 years (in school years 8-11) who completed the National Secondary Students' Diet and Activity survey in 2009-10, which included a web-based self-report questionnaire and height and weight measurements.

Overweight and obesity based on international standard body mass index (BMI) cut-offs for children and adolescents.

Data were analysed for 12 188 students. Just under one in four students were either overweight (18%) or obese (5%). After adjusting for demographic and health-behaviour characteristics, males were more likely than females to be overweight or obese (OR, 1.23; 95% CI, 1.07-1.40; P = 0.004), as were both low (OR, 1.67; 95% CI, 1.40-1.99; P < 0.001) and medium (OR, 1.33; 95% CI, 1.14-1.55; P < 0.001) socioeconomic position (SEP) students compared with high SEP students. Students engaging in low levels of physical activity (OR, 1.21; 95% CI, 1.08-1.36; P = 0.001), more time in small-screen recreation (OR, 1.18; 95% CI, 1.05-1.32; P = 0.005), and short sleep duration (OR, 1.22; 95% CI, 1.05-1.41; P = 0.008) also had higher odds of being overweight or obese.

There is a need for interventions to reduce overweight and obesity during adolescence. Preventive measures should include a focus on facilitating physical activity and reducing sedentary behaviour, as well as promoting adequate sleep, particularly among young people from lower SEP neighbourhoods who appear to be most susceptible.