Estimates of overweight and obesity among samples of preschool-aged children in Melbourne and Sydney

Nutrition Research Newsletter, Dec, 2006

In Australia, childhood obesity is recognized as a significant public health problem, as it is in the United States. Over the past 20 years, the prevalence of overweight and obesity among Australian children has increased from 10% in 1985 to between 19% and 23% to date. Public concern about increased levels of childhood obesity contributed to several Australian states holding summits in 2002 to identify strategies to address the problem. Childhood obesity increases the risk of mortality and morbidity in adulthood. In addition, children who develop obesity in early childhood are twice as likely to maintain the condition throughout life. Obese children are also more likely to experience ongoing health problems in childhood (for example, sleep apnea, asthma, hyperinsulinemia, muscle, and joint problems). A number of longitudinal studies have shown that fatness in later childhood tracks to adulthood. Despite an increase in obesity among school-aged children, little is known about the prevalence of overweight or obesity among Australian children under the age of six years. Until recently, there was lack of consensus among health professionals about the definition of overweight and obesity for this age group. International BMI cut-off points have now been developed for the 2- to 18 year old age group that correspond to the adult definitions of overweight and obesity. To estimate the level of overweight and obesity in Australian preschool-aged children, this study presents the results of two cross-sectional surveys of young children from Melbourne and Sydney. As these two data sets were collected independently, the procedures for data collection differ. However, both studies targeted preschool-aged children.

In Melbourne, the weight and height of 196 children from 12 randomly selected preschools and kindergartens were measured and recorded. In Sydney, data on weight and height of 325 children attending four early childhood centers were extracted from client records. The two studies used the age and gender-specific BMI criteria for classifying overweight and obesity.

The prevalence of Melbourne preschool-aged children considered overweight was 15.3% for boys and 17.3% for girls, with a further 7.1% of boys and 8.2% of girls considered obese. In Sydney, the proportion of children considered overweight was 15.3% for boys and 26.3% for girls. An additional 8.7% of boys and 8% of girls were considered obese.

Although these two studies are not directly comparable and have clear methodological weaknesses, they nonetheless suggest that childhood overweight and obesity is already evident in Australian preschool-aged children. The implication of these results is that overweight and obesity prevention programs will also need to include a focus on families with young children and children's care services.

The general conclusion of these studies is that there is a relatively high prevalence of overweight and obesity among preschool-aged children. A methodologically rigorous prevalence study is required to calculate an accurate level of overweight and obesity in this population. Further research on overweight and obesity with preschool-aged children will need to focus on developing standard methods for measuring height and weight in this age group for population studies. Otherwise, it will remain difficult to accurately determine the true level of overweight and obesity among young children. The clear conclusion from the present study is that to prevent childhood obesity, it is a public health priority that family-based interventions commence early in infancy.

Y. Zuo, M. Norberg, L. M. Wen, et al. Estimates of Overweight and Obesity Among Samples of Preschool-aged Children in Melbourne and Sydney. JADA; Australia. (September 2006). [Correspondence: L. M. Wen, Health Promotion Unit, Central Sydney Area Health Service, Level 9, King George V Building, Missenden Road, Camperdown, NSW 2050, Australia. E-mail: lmwen@email.cs.nsw.gov.au.]