The WHO European Childhood Obesity Surveillance Initiative (or COSI), is a unique system that for over 10 years has measured trends in overweight and obesity among primary school aged children.

COSI involves taking standardized weight and height measurements from over 400,000 children across the WHO European Region, providing nationally representative data for participating countries, as well as a large region-wide data set for analysis of the determinants of childhood overweight and obesity.

This vital collaboration between WHO/Europe and research institutions from across the region provides high-quality data to inform policy and practice to respond to the problem of childhood overweight and obesity.

The sixth round of COSI will take place during the 2021-2023 school years.

The publication from each round of this initiative can be found on the links below:

Round 1 Round 2 Round 3 Round 4 Round 5

NB. Only the National survey data are presented on these pages. Subnational data can be found on the country specific overview pages when you select Child data. Visit the Interactive map, select the country you are interested in and select 'More from this country' in the box below – this will bring you to the countries overview page.

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