[Overweight and obesity in lower-secondary school students in relation to selected behavioural factors. Changes in 2006-2010].

INTRODUCTION: The HBSC (Health Behaviour in School-aged Children) survey, repeatedly carried out among school children in Poland, allows to follow the trends in the occurrence of overweight and obesity as well as changes in selected behaviors, which may influence body weight. THE AIM of this paper is to assess in the years 2006-2010 the prevalence of excess and changes of Polish adolescents' body weight, depending on the pattern of behaviors associated with physical activity and leisure time.

MATERIAL AND METHODS: Data was taken from the 2006 and 2010 HBSC surveys carried out on a total sample of 7133 lower secondary school children. Cluster analysis was applied to define leisure time activity patterns. Combined physical activity index and the average time spent watching television and playing computer games per day were taken as criteria for classification.

RESULTS: In 2006-2010, the proportion of adolescents with overweight or obesity (according to WHO 2007 criteria) increased from 17,7% to 22,0% in boys and from 7,9% to 13,4% in girls. In 2006, the proportion of pupils with overweight and obesity ranged from 12,6% to 17,1% in six defined subgroups, while in 2010 it ranged from 12,6% to 24,7%. No increase of overweight was observed in the cluster representing positive health behaviors. However, the decline in the proportion of adolescents that could qualify to this group is alarming.

CONCLUSION: High physical activity does not always offset the impact of sedentary activities on increase of body mass.