Physical inactivity, sedentary lifestyle and obesity in the European Union

BACKGROUND: Diverging trends of decreasing energy intake and increasing pre valence of obesity suggest that physical inactivity and sedentary lifestyle may be one of the key determinants of the growing rates of overweight/obes ity in Western populations, information about the impact of physical inacti vity and sedentary lifestyles on the prevalence of obesity among the genera l adult population in the European Union is sparse. OBJECTIVES: To estimate the association of leisure-time sedentary and non-s edentary activities with body mass index (BMI, kg/m(2)) and with the preval ence of obesity (BMI > 30 kg/m(2)) in a sample of the 15 member states of t he European Union. METHODS: Professional interviewers administered standardized in-home questi onnaires to 15,239 men and women aged 15 years upwards, selected by a multi -stage stratified cluster sampling with quotas applied to ensure national a nd European representativeness. Energy expenditure during leisure time was calculated based on data on frequency of and amount of time participating i n various physical activities, assigning metabolic equivalents (METS) to ea ch activity. Sedentary lifestyle was assessed by means of self-reported hou rs spent sitting down during leisure time. Multiple linear regression model s with BMI as the dependent variable, and logistic regression models with o besity (BMI > 30 kg/m(2)) as the outcome, were fitted. RESULTS: independent associations of leisure-time physical activity (invers e) and amount of time spent sitting down (direct) with BMI were found. The adjusted prevalence odds ratio (OR) for obesity was 0.52 [95% confidence in terval (CI): 0.43 - 0.64, P < 0.0011 for the upper quintile of physical act ivity ( > 30 METS) compared with the most physically inactive quintile (< 1 .75 METS), A positive independent association was also evident for the time spent sitting down, with an adjusted OR = 1.61(95% CI: 1.33 - 1.95, P < 0. 001) for those who spent more than 35 h of their leisure time sitting down compared with those who spent less than 15 h. Conclusions: Obesity and higher body weight are strongly associated with a sedentary lifestyle and lack of physical activity in the adult population o f the European Union. These results, however, need to be interpreted with c aution due to the cross-sectional design. Nonetheless, they are consistent with the view that a reduction in energy expenditure during leisure time ma y be the main determinant of the current epidemic of obesity.