Association of body mass index and dietary restraint with changes in eating behaviour throughout late childhood and early adolescence: a 5-year study.

OBJECTIVES To describe patterns of dietary behaviours specific to low quality snacking, fruit and vegetable, and fast food consumption during the transition from childhood to adolescence and to examine how these behaviours are associated with tendencies towards dietary restraint and the occurrence of overweight and obesity in mid-adolescence. DESIGN A 5-year follow-up of self-reported eating. Hierarchical linear modelling was utilised to explore the relationship between dietary changes and body mass index (BMI) and dietary restraint while controlling for physical activity and smoking. SETTING The sample was derived from students participating in the Quebec Heart Health Demonstration Project, and represents rural, suburban and inner city youths. SUBJECTS A sample of 561 girls and 627 boys in the fourth, sixth, seventh and ninth grades. RESULTS Overall the sample was characterised by a decrease in fruit and vegetable consumption and increase in low quality snacking, and a decrease in fast food consumption over the 5-year follow-up. Dietary restraint and BMI were found to be associated with dietary behaviour. Lower than average dietary restraint was associated with a lower frequency of fast food consumption and greater increase in low quality snacking over the 5-year period. Higher than average dietary restraint was associated with lesser frequency of low quality snacking at baseline. Having a BMI in the obese range was associated with more frequent fast food consumption in the fourth grade and a more rapid drop in fast food consumption across the 5-year period. CONCLUSIONS Dietary behaviours are associated with the psychological construct dietary restraint and with weight status in this population of adolescents.