In contrast to the situation among the adult population, due to the low incidence of obesity-related diseases among children and young people no threshold values have been set in respect of the amount of body fat mass that presents a danger to their health. Using the statistical distribution of reference values, BMI values, which 90% of children and young people do not exceed, are classed as overweight and values, which 97% of children and young people do not exceed, are classed as obese. The ranges used in the GMON are based on studies from [Kromeyer et al 2001].
| Classification | Traffic light colour | 7-8 years | 9-10 years | 11-12 years | 13-14 years | 15-16 years | 17-18 years |
| Underweight | Yellow | < 13.8 | < 14.3 | < 15.1 | < 16.4 | < 17.5 | < 18.2 |
| Normal weight | Green | 13.8-18.9 | 14.3-20.4 | 15.1-22.0 | 16.4-23.7 | 17.5-24.8 | 18.2-24.0 |
| Overweight | Yellow | 18.9-20.9 | 20.4-23.0 | 22.0-25.0 | 23.7-26.7 | 24.8-27.6 | 24.0-27.8 |
| Obese | Red | > 20.9 | > 23.0 | > 25.0 | > 26.7 | > 27.6 | > 27.8 |
Table: BMI classification according to age (girls)
| Classification | Traffic light colour | 7-8 years | 9-10 years | 11-12 years | 13-14 years | 15-16 years | 17-18 years |
| Underweight | Yellow | < 14.0 | < 14.4 | < 15.2 | < 16.2 | < 17.3 | < 18.4 |
| Normal weight | Green | 14.0-18.6 | 14.4-20.2 | 15.2-21.8 | 16.2-23.4 | 17.3-24.0 | 18.4-24.0 |
| Overweight | Yellow | 18.6-20.6 | 20.2-22.8 | 21.8-25.0 | 23.4-26.6 | 24.0-27.8 | 24.0-28.6 |
| Obese | Red | > 20.6 | > 22.8 | > 25.0 | > 26.6 | > 27.8 | > 28.6 |
Table: BMI classification according to age (boys)
If a child's BMI approaches the threshold values or exceeds these action is required in order to prevent risks to health.
Express reference is made to the fact that at the age of pre-puberty and puberty additional more drastic measures to reduce BMI (such as a reduction of calorie utilisation using medication), if these are absolutely necessary, require medical check-ups.