Longitudinal associations of energy balance-related behaviours and cross-sectional associations of clusters and body mass index in Norwegian adolescents

Background: Insight into the role of energy balance-related behaviours (EBRB) is of great importance when it comes to prevention of weight gain and design of interventions tailored to target these behaviours. Objectives: First, the present study examines the longitudinal association of four EBRB in Norwegian adolescents. Second, it aims to examine whether clusters of EBRB are cross-sectionally associated with being overweight. Design: The present study is part of the 'Fruits and Vegetables Make the Marks' project. The study sample consists of twenty control schools in two Norwegian counties. Methods: Survey questionnaires were completed by 884 pupils with an average age at baseline, September 2001, of 11.8 years. In the follow-up surveys in May 2002 and May 2005, a total of 809 and 724 adolescents participated, respectively. Four EBRB were measured: habitual fruit and vegetable intake, snacking and soda consumption, television and computer use and physical activity. Results: Results of the associations between EBRB were similar for boys and girls. The odds, ranging from 1.14 to 12.06, were mostly significant. One out of four clusters, the unhealthy cluster, was significantly and cross-sectionally associated with overweight and obesity. Conclusions: Longitudinal associations of EBRB show that it is important to start early with interventions that aim to prevent unhealthy behaviours becoming habitual. These behaviours should be targeted at the same time as they tend to co-occur. More research, preferably longitudinal and more objective, is needed to investigate associations between health behaviours and body weight among adolescents.