Physical activity in normal and overweight adolescents

Nutrition Research Newsletter, August, 2005

The prevalence of overweight and obesity in children and adolescents is increasing worldwide. Physical inactivity or being sedentary is often thought to be an important contributing factor in the development and maintenance of childhood obesity. However, whether overweight youngsters are less physically active than their normal weight peers, remains a largely understudied issue. In addition, the differential role of psychosocial factors for overweight and normal weight adolescents is important to understand. Therefore, a recent study in Belgium examined differences in psychosocial correlates of physical activity, and in physical activity within different contexts, and sedentary behaviors between normal weight and overweight adolescents. The study also explored whether the prediction of physical activity by the psychosocial correlates is different in normal weight and overweight adolescents.

A community sample of 6078, comprising of 11 year olds to 19 year olds from 38 secondary schools in the Flemish part of Belgium, made up this study. The adolescents completed a validated computerized questionnaire about physical activity, sedentary behaviors and psychosocial correlates. Height and weight were self-reported and BMI was calculated. Differences in mean scores on the psychosocial correlates and on the self-rated physical activity were analyzed between the normal weight (n=5563) and the overweight (n=515) group. Adolescents with a BMI <25 were considered to be of normal weight and adolescents with a BMI >25 were considered overweight.

Overweight adolescents do significantly less intense physical activities and have less favorable psychosocial correlates related to physical activity than their normal weight peers. However, the strength of the associations between psychosocial variables and total physical activity were comparable in overweight and normal weight adolescents. More support from family and friends, more fun in physical activity, higher self-efficacy, the perception of more competition benefits and the perception of less lack of interest, were all associated with higher total levels of physical activity.

This study showed that overweight adolescents do fewer intense physical activities and have fewer favorable psychosocial correlates related to physical activity than their normal weight counterparts. Some of the limitations of this study include that the data was obtained by self-report. Therefore, there may be some underreporting of overweight and it might have been helpful to have some objective measures of activity, such as an accelerometer. However, the strength of this study was the investigation of both physical activity and related psychosocial correlates in a large community sample.

Ilse De Bourdeaudhuij, Johan Lefevre, Benedicte Deforche, et al. Physical Activity and Psychosocial Correlates in Normal and Overweight 11 to 19 Year Olds. Obesity Res; 13(6): 1097-1105 (June 2005). [Correspondence: Ilse De Bourdeaudhuij, Department of Movement and Sport Sciences, Ghent University, Watersportlaan 2, 9000 Gent, Belgium. E-mail: Ilse.Debourdeaudhuij@Ugent.be]