Summary Background Comparable global data on health and nutrition of school-aged children and adolescents are scarce. We aimed to estimate age trajectories and time trends in mean height and mean body-mass index (BMI), which measures weight gain beyond what is expected from height gain, for school-aged children and adolescents. Methods For this pooled analysis, we used a database of cardiometabolic risk factors collated by the Non-Communicable Disease Risk Factor Collaboration. We applied a Bayesian hierarchical model to estimate trends from 1985 to 2019 in mean height and mean BMI in 1-year age groups for ages 5–19 years. The model allowed for non-linear changes over time in mean height and mean BMI and for non-linear changes with age of children and adolescents, including periods of rapid growth during adolescence. Findings We pooled data from 2181 population-based studies, with measurements of height and weight in 65 million participants in 200 countries and territories. In 2019, we estimated a difference of 20 cm or higher in mean height of 19-year-old adolescents between countries with the tallest populations (the Netherlands, Montenegro, Estonia, and Bosnia and Herzegovina for boys; and the Netherlands, Montenegro, Denmark, and Iceland for girls) and those with the shortest populations (Timor-Leste, Laos, Solomon Islands, and Papua New Guinea for boys; and Guatemala, Bangladesh, Nepal, and Timor-Leste for girls). In the same year, the difference between the highest mean BMI (in Pacific island countries, Kuwait, Bahrain, The Bahamas, Chile, the USA, and New Zealand for both boys and girls and in South Africa for girls) and lowest mean BMI (in India, Bangladesh, Timor-Leste, Ethiopia, and Chad for boys and girls; and in Japan and Romania for girls) was approximately 9–10 kg/m 2 . In some countries, children aged 5 years started with healthier height or BMI than the global median and, in some cases, as healthy as the best performing countries, but they became progressively less healthy compared with their comparators as they grew older by not growing as tall (eg, boys in Austria and Barbados, and girls in Belgium and Puerto Rico) or gaining too much weight for their height (eg, girls and boys in Kuwait, Bahrain, Fiji, Jamaica, and Mexico; and girls in South Africa and New Zealand). In other countries, growing children overtook the height of their comparators (eg, Latvia, Czech Republic, Morocco, and Iran) or curbed their weight gain (eg, Italy, France, and Croatia) in late childhood and adolescence. When changes in both height and BMI were considered, girls in South Korea, Vietnam, Saudi Arabia, Turkey, and some central Asian countries (eg, Armenia and Azerbaijan), and boys in central and western Europe (eg, Portugal, Denmark, Poland, and Montenegro) had the healthiest changes in anthropometric status over the past 3·5 decades because, compared with children and adolescents in other countries, the...

<b><i>Background:</i></b> Children are becoming less physically active as opportunities for safe active play, recreational activities, and active transport decrease. At the same time, sedentary screen-based activities both during school and leisure time are increasing. <b><i>Objectives:</i></b> This study aimed to evaluate physical activity (PA), screen time, and sleep duration of girls and boys aged 6–9 years in Europe using data from the WHO European Childhood Obesity Surveillance Initiative (COSI). <b><i>Method:</i></b> The fourth COSI data collection round was conducted in 2015–2017, using a standardized protocol that included a family form completed by parents with specific questions about their children’s PA, screen time, and sleep duration. <b><i>Results:</i></b> Nationally representative data from 25 countries was included and information on the PA behaviour, screen time, and sleep duration of 150,651 children was analysed. Pooled analysis showed that: 79.4% were actively playing for &#x3e;1 h each day, 53.9% were not members of a sport or dancing club, 50.0% walked or cycled to school each day, 60.2% engaged in screen time for &#x3c;2 h/day, and 84.9% slept for 9–11 h/night. Country-specific analyses of these behaviours showed pronounced differences, with national prevalences in the range of 61.7–98.3% actively playing for &#x3e;1 h/day, 8.2–85.6% were not members of a sport or dancing club, 17.7–94.0% walked or cycled to school each day, 32.3–80.0% engaged in screen time for &#x3c;2 h/day, and 50.0–95.8% slept for 9–11 h/night. <b><i>Conclusions:</i></b> The prevalence of engagement in PA and the achievement of healthy screen time and sleep duration are heterogenous across the region. Policymakers and other stakeholders, including school administrators and parents, should increase opportunities for young people to participate in daily PA as well as explore solutions to address excessive screen time and short sleep duration to improve the overall physical and mental health and well-being of children.

In 2015-2017, the fourth round of the World Health Organization (WHO) European Childhood Obesity Surveillance Initiative (COSI) was conducted in 36 countries.National representative samples of children aged 6-9 (203,323) were measured by trained staff, with similar equipment and using a standardized protocol. This paper assesses the children's body weight status and compares the burden of childhood overweight, obesity, and thinness in Northern, Eastern, and Southern Europe and Central Asia. The results show great geographic variability in height, weight, and body mass index. On average, the children of Northern Europe were the tallest, those of Southern Europe the heaviest, and the children living in Central Asia the lightest and the shortest. Overall, 28.7% of boys and 26.5% of girls were overweight (including obesity) and 2.5% and 1.9%, respectively, were thin according to the WHO definitions. The prevalence of obesity varied from 1.8% of boys and 1.1% of girls in Tajikistan to 21.5% and 19.2%, respectively, in Cyprus, and tended to be higher for boys than for girls. Levels of thinness, stunting, and underweight were relatively low, except in Eastern Europe (for thinness) and in Central Asia. Despite the efforts to halt it, unhealthy weight status is still an important problem in the WHO European Region.

Establishment of the WHO European Childhood Obesity Surveillance Initiative (COSI) has resulted in a surveillance system which provides regular, reliable, timely, and accurate data on children's weight status-through standardized measurement of bodyweight and height-in the WHO European Region. Additional data on dietary intake, physical activity, sedentary behavior, family background, and school environments are collected in several countries. In total, 45 countries in the European Region have participated in COSI. The first five data collection rounds, between 2007 and 2021, yielded measured anthropometric data on over 1.3 million children. In COSI, data are collected according to a common protocol, using standardized instruments and procedures. The systematic collection and analysis of these data enables intercountry comparisons and reveals differences in the prevalence of childhood thinness, overweight, normal weight, and obesity between and within populations. Furthermore, it facilitates investigation of the relationship between overweight, obesity, and potential risk or protective factors and improves the understanding of the development of overweight and obesity in European primary-school children in order to support appropriate and effective policy responses.

From 1985 to 2016, the prevalence of underweight decreased, and that of obesity and severe obesity increased, in most regions, with significant variation in the magnitude of these changes across regions. We investigated how much change in mean body mass index (BMI) explains changes in the prevalence of underweight, obesity, and severe obesity in different regions using data from 2896 population-based studies with 187 million participants. Changes in the prevalence of underweight and total obesity, and to a lesser extent severe obesity, are largely driven by shifts in the distribution of BMI, with smaller contributions from changes in the shape of the distribution. In East and Southeast Asia and sub-Saharan Africa, the underweight tail of the BMI distribution was left behind as the distribution shifted. There is a need for policies that address all forms of malnutrition by making healthy foods accessible and affordable, while restricting unhealthy foods through fiscal and regulatory restrictions.