Food and beverage portion sizes in Australian children: a secondary analysis of 1995 and 2007 national data.

BACKGROUND
Portion size of foods is reported to contribute to the rise in obesity prevalence. However, evidence of changes in portion size for commonly consumed foods in Australia is lacking. The aim was to evaluate whether Australian child and adolescent portion sizes of selected foods changed from 1995 to 2007.

METHODS
Time-series study, comparing dietary data from two national cross-sectional surveys in nationally representative population survey of Australian households. The dietary data was from children aged 2-16 years who participated in the 1995 National Nutrition Survey (n = 2198) and 2007 Australian National Children's Nutrition and Physical Activity Survey (n = 4799).

RESULTS
Differences were found across survey years in median portion size of common foods and beverages assessed by 24-hour recalls for age and sex categories. Of the 61 foods items evaluated across the whole population sample, portion size increased in 18 items, decreased in 22, with no change in 20, although the magnitude of change varied by age and sex. Decreases in portion size were detected for most dairy products, breakfast cereal, some packaged snack foods and vegetables, p < 0.0001. Increases were detected for cooked chicken, mixed chicken dishes, bacon and ham (p < 0.0001), cooked meat (p < 0.05), fish (p < 0.01) and pizza (p < 0.0001). No significant changes were detected for many items including white and wholemeal bread, mincemeat, chocolate and soft drink.

CONCLUSIONS
Small changes in portion sizes were detected over 12 years in Australian children and adolescents with the degree of change varying by sex, age and food group. Knowledge of usual portion sizes could inform programs targeting appropriate serving sizes selection in children and adolescents.