Objective: Data of Jena children (Germany) show increases in the prevalence estimates of overweight and obesity between 1975 and 2001. Our objective was to determine if these increases contribute to changes in the distribution of body mass index (BMI) in the entire population of children. The decade 1985-1995, which includes the time of German reunification, is of particular interest because of the significant socio-economic changes in East Germany, in which Jena is located.
Design and subjects: The analyses were based on data from four cross-sectional growth studies in 7- to 14-year-old children performed in Jena, Germany, in 1975 (n=2013), 1985 (n=1534), 1995 (n=1906) and 2001 (n=1918). Overweight and obesity were estimated by German reference data and the reference of Cole et al. Mean difference plots were used to investigate the changes in the BMI distributions within sexes between the studies.
Results: Between 1985 and 1995, the prevalence of overweight and obesity increased significantly in both sexes, whereas nonsignificant changes were found between 1975 and 1985. Although there is a tendency towards increased overweight between 1995 and 2001, the differences were nonsignificant. Comparing data from 1975 and 1985, the mean difference plots showed virtually no changes in the BMI distribution. In the plots comparing the BMI distribution for 1985 data and 1995 data, the whole distribution tended to shift upwards with a greater shift in the upper BMI range. The entire population of children in Jena gained weight during this period of time. This increase may be linked to a transition towards a more Western lifestyle, that is, usually by lower energy expenditure and nutritional transitions, caused by the process of reunification of Germany in 1989.
Conclusions: Weight gain appears to be a characteristic feature of the entire population studied and does not seem to be a separate problem of the obese children. This suggests that reported changes in the prevalence may be underestimating the looming public health crisis.