The childhood obesity working group was established by the IOTF because overweight and obesity in children and adolescents is increasing dramatically. However, the lack of a common assessment method for children has hindered international comparisons of childhood obesity rates. The group therefore set out to present a global picture of overweight and obesity among paediatric populations by first identifying a standard assessment method needed.

A meeting was held in Dublin, Ireland in June 1997 to discuss methods of assessment. A consensus was reached among the group of experts present at the meeting to use BMI as a reasonable index of adiposity in children and adolescents. The group also suggested how cut-off values for overweight and obesity could be identified and that these should be based on an international reference population of children and adolescents. The proceedings from this meeting will be published in the American Journal of Clinical Nutrition this summer.

The provisional reference population underpinning the BMI cut-offs is based on 5 nationally representative datasets all of which satisfied the four criteria of large sample size (more than 10,000 subjects), national or regional representation minimum age range (6-18 years) and quality control in the data collection. The countries selected for the provisional population, (Brazil, Britain, Netherlands, Hong Kong and USA), were sufficiently homogeneous giving an overall sample of 78,235 children. The reference population would be considerably strengthened by the addition of samples from Africa and Asia. Additional datasets could be added to the reference population as long as they satisfy the criteria for inclusion. 

The methodology and cut-offs for underweight, overweight and obesity for children aged 6-18 years have been written up and submitted to a medical journal for publication.

Having the new standard international BMI cut-offs the childhood obesity working group applied them to standard Demographic and Health Survey datasets that included weight and height measurements for 5 year old children from 25 developing countries. The prevalence of overweight children in these countries has already been presented at the Paris satellite childhood obesity meeting organised by the European Childhood obesity Group last September. Further analysis looking at various socio-economic indicators is presently being carried out. 

The next task for the group is to determine the prevalence of overweight 10 and 15 year olds worldwide. This project requires the collation of anthropometric datasets from as many countries as possible. It is an ambitious project which requires substantial effort to track and obtain data from as many countries as possible. The data need not be nationally representative. Regional or local studies are acceptable. The sample size should be at least more than 100 for each age group and gender. The group has also defined exclusion criteria for datasets which are of poor quality. A number of valid datasets are already available for analysis and the group wish to extend their acknowledgement to all the investigators who sent their data for analysis.

The group is very eager to present as broad a picture of the overweight situation among children and adolescents worldwide. Any information on the availability of data is welcome and should be addressed to Dr Mary Bellizzi, project co-ordinator at the IOTF secretariat.

Having presented a coherent picture of the situation of overweight children the next step would be to move on to next phase of activities. Some discussion has already been held and it is felt that the group may have a lot to contribute towards the prevention and management of childhood obesity.