Text from the Indicator Report 2022 

The Body Mass Index (BMI) is a benchmark that is used to measure excess weight and especially obesity. It is calculated by dividing the body weight in kilograms by the square of an individual’s height in metres. This calculation does not take age-specific and gender-specific differences into account. Nor does it indicate the individual body mass composition. However, obesity and excess weight among children and adolescents are defined by taking account also of age and gender. In order to determine if people suffer from obesity or excess weight, the individual BMI value is compared with a defined comparison group (reference population). The percentile reference values according to Kromeyer-Hauschild as recommended by the “Arbeitsgemeinschaft Adipositas im Kinder- und Jugendalter” are used as a comparative benchmark. According to these values, children and adolescents are considered to be overweight if their BMI value is above the 90th age- and gender-specific percentile of the reference population (> P90). This means that they fall within the range of those 10 % of the reference group with the highest BMI values. A BMI value above the 97th percentile of the reference population (that is, as high as the 3 % of adolescents with the highest BMI values) is classified as obesity (> P97). For example, girls and boys aged three with a BMI of 18.8 kg/m² are considered to be obese. These reference values are based on details of body size and weight that were recorded between 1985 and 1998 in various regions of Germany, using different methods.

The data for the indicator is gathered by the Robert Koch Institute. The German Health Interview and Examination Survey for Children and Adolescents (KiGGS – referred to as the KiGGS baseline study) for the period 2003 to 2006 delivered the first nationwide representative results. New measurement data is available for the period 2014 to 2017 from the second follow-up survey of the KiGGS study (KiGGS Wave 2). In order to allow the data to be compared in a suitable way, the results were age standardised to the reference date 31 December 2015 of the intercensal population update.

For the time period 2014 to 2017, 3.9 % of the 3 to 10-year-olds and 8.0 % of the 11 to 17-year-olds were classified as obese. While there were no differences between the sexes in the 3 to 10 years age group, the rates for the 11 to 17-year-olds were 7.2 % for girls and 8.7 % for boys. In the period from 2003 to 2006, the proportion of 3 to 10-year-olds with obesity was about 5.2 %; among the 11 to 17-year olds, it was about 8.3 %. Again, girls and boys in the age from 3 to 10 years were equally affected. The figure for the 11 to 17-year-olds broke down into 8.2 % of the girls and 8.4 % of the boys. The obesity rate has therefore fallen more sharply among 3 to 10-year-olds than in the 11 to 17 age group. While it fell by 1.0 percentage points among girls aged 11 to 17, it showed a slight increase of 0.3 percentage points among boys in that age group.

The proportion of adolescents suffering from excess weight including obesity (> P90) did not change much compared with the period 2003 – 2006 (decrease by 0.6 percentage points to 12.3 % for 3 to 10-year olds, increase by 0.6 percentage points to 18.7 % for 11 to 17-year-olds).

Important factors in the development of overweight are dietary and exercise behaviour, which differ – when looking at the results – in terms of socioeconomic status (SES). The results from KiGGS Wave 2 confirm that 3 to 17-year-old children and adolescents with a low socioeconomic status eat unhealthy more often than their peers from socially better-off families and exercise less frequently. The risk of overweight and obesity is about 3 to 4 times higher for children and adolescents with low SES than in the upper status group (about 20 % of the study population).

The synoptic table provides information about the evaluation of the indicator in previous years. It shows if the weather symbol assigned to an indicator was rather stable or volatile in the past years. (Evaluation of the Indicator Report 2022 )