Since COSI started in 2007/2008, over half a million children (6-10 years old) are measured and weighed according to the COSI protocol¹ in 45 countries, every 3 years. Particular attention was given to the last two years marked by a global pandemic caused by COVID-19. Prevalence values of overweight and obesity are calculated by age group, using the cut-offs recommended by WHO² to compute BMI-for-age Z-scores. In the 1st (2008) and 2nd (2010) rounds, prevalence of childhood overweight (including obesity) varied from 19.3% and 18.4% in Belgium to 49.8% and 42.5% in Italy, respectively. In both rounds, multi-country comparisons suggested the presence of a north−south gradient with the highest level of overweight found in southern European countries³. The latest data from 4th round (2016) showed a significant decrease in the prevalence of both overweight and obesity which was recorded in Greece, Italy, Portugal, Spain and Slovenia, ranging from 4 to 12, and 3 to 7 percentage points for boys and girls, respectively. Belgium, Czechia and Norway have stable prevalence; whereas the picture is less definite in Bulgaria, Latvia and Lithuania⁴. The 5th (2019) and 6th (2022) rounds were marked by a 2 year COVID-19 pandemic. Due to the need to understand the impact of COVID-19 on the children’s and families’ lifestyles, 30 COSI countries are now collecting data on how the governmental measures put in place to mitigate the spread of COVID-19, impacted families’ and children’s daily lifestyles and nutritional status. COSI progress throughout the last decades enabled to identify the key issues that need to be addressed and mobilized governmental action to counteract the development of childhood obesity, potentially exacerbated by the health, social economic and constraints lived in the recent years.