Dietary intake, physical activity and TV viewing as mediators of the association of socioeconomic status with body composition: a cross-sectional analysis of Australian youth.
BACKGROUND
There is emerging evidence of socioeconomic gradients in adiposity among Australian youth. Behavioral mechanisms for these trends are unexplained.


METHODS
In total, 194 South Australian children (97 boys, 11.48+/-0.43 years; 97 girls, 11.60+/-0.38 years) were assessed for pubertal status, stature, weight, skinfolds and waist girth. Socioeconomic status (SES) was represented by postcode of residence (Socioeconomic Index for Areas) and parent education. Children reported moderate-to-vigorous physical activity (MVPA), TV viewing (TV) and dietary intake (daily energy intake as a ratio of predicted basal metabolic rate (DEI/BMR); and fat intake), using three x 24 h recall. Path analysis (partial least-squared method) was used to analyze the independence and interdependence of pathways linking SES, anthropometric variables and measured behaviors.


RESULTS
SES was negatively associated with waist girth and skinfolds in girls, and waist girth in boys. In models including behavioral variables, these SES gradients in girls were largely unattenuated; accordingly, physical activity and dietary intake were not confirmed as mediators of the association of SES and girls' adiposity. In boys there was evidence that the negative relationship between SES and waist girth was mediated by fat intake.


CONCLUSIONS
The inverse relationships between SES and girls' adiposity were unexplained by the behavioral attributes measured in this study. Mediators of SES gradients in youth adiposity remain elusive, and may require intensive methodologies to explicate.
Dollman
J
J
Nutritional Physiology Research Center, University of South Australia, Adelaide, South Australia, Australia. james.dollman@unisa.edu.au
Ridley
K
K
Magarey
A
A
Martin
M
M
Hemphill
E
E
D000273:Adipose Tissue / Q000502:physiology; D001823:Body Composition / Q000502:physiology; D001827:Body Height / Q000502:physiology; D049628:Body Size / Q000502:physiology; D001835:Body Weight / Q000502:physiology; D002648:Child; D004032:Diet; D004041:Dietary Fats / Q000008:administration & dosage; D004522:Educational Status; D002149:Energy Intake / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D007899:Leisure Activities; D008297:Male; D015233:Models, Statistical; D012111:Residence Characteristics; D012737:Sex Factors; D012885:Skinfold Thickness; D012959:Socioeconomic Factors; D013690:Television
D004041:Dietary Fats