Predictors of Overweight and Obesity in Five to Seven-year-old Children
Background: Childhood obesity is a serious public health problem and epidemiological studies are important to identify predictive factors. It is the aim of this study to analyse factors associated with overweight/obesity in samples of German children.
Methods: 35,434 five to seven year-old children (50.9% boys) participated in cross-sectional studies between 1991 and 2000 in several rural and urban areas in East and West Germany. Weight and height were measured and body mass index was calculated. International cut-off points, recommended by the International Obesity Task Force, were used to classify childhood overweight and obesity.
Predictive modelling was employed to analyse independently associated factors, using logistic regression to adjust for confounding.
Results: 15.5% were overweight, and 4.3% were obese. Female sex, other than German nationality, smoking in the living place and increasing birth weight were found to increase the odds of overweight and obesity, while increasing educational level, living space >75 m and breastfeeding for more than three months were inversely associated.
Conclusion: The findings add to the evidence informing public health action, both through health promotion strategies (promoting breastfeeding, tackling smoking) and wider societal change management (addressing children from migrant families and families with low educational level).

Recent evidence from the German Health Interview and Examination Survey for Children and Adolescents (KiGGS) provides nationally representative data with respect to overweight and obesity in children and adolescents (three to 17 years old) for the first time. 15% were classified as overweight and 6.3% were classified obese (exceeding the 90 and 97 percentile of the German reference data, respectively).

Obesity cannot only result in many adverse health outcomes such as respiratory, cardiovascular or metabolic complications as well as body dissatisfaction, but has itself a multifactorial aetiology. Thus, previous studies examined a large number of potential predictors of childhood overweight and obesity.

Apart from demonstrating a substantial burden of overweight and obesity in children and adolescents, the KIGGS study showed overweight or obesity to be associated with lower socioeconomic status, migration background and the mother being overweight. Other studies in samples of German children have identified further factors associated with a lower prevalence of overweight/obesity, e.g. high parental education, and factors consistently associated with an increased prevalence, such as maternal smoking during pregnancy. A review of international studies found socio-economic status to be inversely associated with overweight/obesity. Ethnicity or nationality have also been linked in the patterning of overweight and obesity, as well as the consumption of energy-dense foods. Meta-analyses have shown a protective effect of breastfeeding on the risk of overweight/obesity.

The cited studies used various different cut-off points to categorise overweight/obesity. Most studies used population-based cut-offs depending on the observed distribution at a given percentile and only a few studies used the cut-offs suggested by Cole et al. Cole and co-authors have developed a definition of overweight and obesity based on pooled samples from several countries, providing age- and sex-specific cut-off points. These reference values are recommended for international comparison.

We have previously reported prevalence data for large samples of five to seven-year-old German children (N = 35,434), using the cut-off points proposed by Cole and co-authors. We found significantly increasing prevalences of overweight and obesity in both East and West Germany from 1991 to 2000. Overall, the prevalence of overweight was 15.5%, and the prevalence of obesity was 4.3%.

The aim of this paper is to investigate predictors of childhood overweight and obesity, drawing on the same data.