Definition of overweight and obesity in children

Overweight encompasses pre-obesity and obesity that are medical conditions marked by an abnormal and/or excessive accumulation of body fat that presents a risk to health ( WHO 2019a  ). Obesity is a chronic relapsing disease ( WHO 2022 (pdf)  ), which in turn acts as a gateway to a range of other non-communicable diseases, such as diabetes, cardiovascular diseases and cancer. The 11th Revision of the International Classification of Diseases (ICD-11)  lists them under Endocrine, nutritional or metabolic diseases ( WHO 2023a , WHO 2023b ).

For information focussed on obesity prevention in adulthood please see here.

Overweight and obesity can be identified in children using simple measures like weight, height or length (recumbent length is measured in children under 2 years of age, and standing height is measured in children ≥2 years old), and Body Mass Index (BMI). The BMI is a surrogate marker of fatness and can be calculated by dividing a person’s weight in kilograms by the square of the person’s height in metres (kg/m²). In younger children, weight-for-height (or weight-for-length for children under 2 years of age) or BMI-for-age are most commonly used; in children aged over 5 years, the BMI-for-age is used. Alternative ways of assessment such as arm circumference-for-age, triceps and subscapular skinfold measurements-for-age are also applied in young children to identify fat deposition ( WHO 2006 ).

As adipose tissue distribution varies significantly in children and adolescents by age and sex, these measures are then interpreted with the help of sex- and age- specific thresholds. The most commonly used definitions of overweight and obesity in children, using the different available thresholds from growth standards or reference data, described in Table 1.

Table 1: Most commonly used definitions of overweight and obesity in children 

Prevalence of pre-obesity and obesity in children in Europe

Information on the prevalence of overweight and obesity in children and adolescents is not collected routinely and in a systematic way across age groups or countries. Nonetheless, the UNICEF/WHO/World Bank Group Joint Child Malnutrition Estimates provide modelled estimates of the prevalence of overweight in children under 5 years of age for some of the EU countries and the WHO European Childhood Obesity Surveillance Initiative (or COSI) collects measured weight and height data of children aged 7-9 years in a comparable way across most of the EU countries. Other national efforts have collected measured weight and height data for adolescents aged 10-19 years ( WHO GHOa  ). The most recent data on prevalence of overweight and obesity in children across the EU are presented in Table 2 and Table 3, respectively.
 

Table 2: Prevalence of overweight in children under 5 years, 7-9 years and 10-19 years of age 

Table 3: Prevalence of obesity in children 7-9 years and 10-19 years of age 

Factors related to obesity in children

Obesity in childhood is a multifactorial condition that is influenced by biological, socioeconomic and environmental factors. There are factors operating at different stages of the life cycle period (i.e. perinatal period, infant and young child, child and adolescent) which can contribute to overweight and obesity in childhood ( WHO 2016 (pdf)   , UNICEF 2019 (pdf)   ). Table 4 presents modifiable risk factors related to (the onset and progression of) overweight and obesity in childhood, and the nature of the relationships between these factors and obesity in children. Further to these biological and environmental factors, socioeconomic factors are linked with overweight and obesity in children. In high-income countries, children in lower socio-economic groups have a higher risk of obesity; the opposite is happening in low- and middle- income countries ( WHO 2016 ). ‘None of these upstream causal factors are in the control of the child’ ( WHO 2016 ). Governmental and public health policies are crucial in addressing the risks by bringing changes to the physical environment and by supporting the families and educators.

For more information on factors related with overweight and obesity in adults please see here.
 

Table 4: Modifiable risk factors related to obesity in childhood

Disease and economic burden related to pre-obesity and obesity in childhood

Disease burden

According to the Global Burden of Disease 2021 study, approximately 21 100 Disability-Adjusted Life Years (DALYs) were attributed to high BMI at ages 0-19 years in the EU-27 in 2021. DALYs attributed to high BMI at ages 10-19 years were approximately 1.9 and 2.6 times higher than DALYs attributed to high BMI at ages 5-9 years and <5 years, respectively; DALYs attributed to high BMI at ages 5-9 years were approximately 1.4 times higher than DALYs attributed to high BMI at ages <5 years ( IHME 2024  ). 
 

Pre-obesity and obesity in childhood can have an effect on children’s immediate health and quality of life (for example, breathing difficulties, increased risk of fractures, hypertension, early markers of cardiovascular disease, insulin resistance and psychological effects) ( WHO 2021a ),  Council of the European Union 2018 ). In addition, overweight in early childhood has been shown to increase the likelihood of obesity in later childhood but also tracks to adulthood. 
 

View map: Disability-Adjusted Life Years (DALYs)/100 000 attributable to High body-mass index in children aged 5-9 years in EU Member States 

View map: Disability-Adjusted Life Years (DALYs)/100 000 attributable to High body-mass index in children aged 10-19 years in EU Member States 

Economic burden

Evidence on the lifetime cost of obesity in childhood is scarce. Most studies have concentrated on direct healthcare expenditure without taking into account other costs such as those incurred by the early onset of noncommunicable diseases which can have an important economic and societal impact ( WHO 2016 ). In addition, further to the short-term direct cost consequences of childhood obesity, the indirect consequences stemming from the association of childhood obesity with adulthood obesity should be considered ( WHO 2016 ). Moreover, the ‘relationship between childhood obesity and educational outcomes can constrain the formation of human capital and future socio-economic status’ ( OECD 2019  ).

A recent meta-analysis ( Ling et al 2022 ) quantified the economic burden (in 2022 US $) of childhood pre-obesity or obesity relative to healthy weight, based on the results of 48 studies. The increased costs of a child having obesity were 1.3-3 times higher to the increased costs of a child having pre-obesity (for both increased costs relative to a child of healthy weight) for annual total medical costs, nonhospital healthcare, outpatient visits, and annual prescribed medication, and more than 17 times higher for hospitalisation costs (cost per hospitalisation). Childhood obesity resulted in much higher indirect costs (i.e. costs in adulthood) than direct healthcare costs (i.e. costs in childhood). Reducing adolescent pre-obesity and obesity in 2000 by 1% would save $ 99.41 per capita in lifetime medical costs ( Ling et al 2022  ).

Table 5: Economic burden of childhood pre-obesity or obesity (increased annual healthcare costs)

The Swedish Institute for Health Economics examined the differences between the increased total lifetime costs of a child (6 year-old) having pre-obesity or obesity with those of an adolescent (15 year-old) having pre-obesity or obesity in Sweden (both relative to a child or adolescent with healthy weight, respectively) ( IHE 2022 (pdf)  ). The increased total lifetime costs for a child with obesity were higher for females compared to males (SEK 429 000 vs. SEK 257 000). The increased total average societal costs over a lifetime for an adolescent with obesity were approximately 2.4 and 1.5 times higher for males and females, respectively, compared to the costs calculated for a child with obesity. For a child with pre-obesity, the increased societal costs were considerably lower and more similar between males and females (~SEK 150 000). The increased societal costs for an adolescent with pre-obesity were 1.4 and 3 times higher for males and females, respectively, compared to the cost of a child with pre-obesity. For both pre-obesity and obesity, production loss represented the greater proportions of costs (~75%).

Table 6: Economic burden of pre-obesity or obesity in childhood or adolescence (increased total lifetime costs)

For more information on the disease and economic burden related with pre-obesity and obesity in adults please see here.

Policy recommendations on prevention of overweight and obesity in childhood

A whole-of-life approach is recommended addressing the multiple causes of childhood obesity and bringing change to different aspects of the environment (macro-social, family, educational, leisure and living, digital and audiovisual, and health) ( EESC 2023 ). Such approach should ensure that social exclusion is prevented and that children in vulnerable situations or of lower socioeconomic backgrounds are reached ( Council of the European Union 2018 , Council of the European Union 2021 ) .

Many EU Member States have in place strategies and national guidelines for the primary prevention of overweight and obesity in childhood. Some of the strategies and guidelines address the general population; these include national dietary guidelines, physical activity guidelines, provision of information to the population through food and menu labelling, public awareness campaigns, and mobile apps, that empower the population to make healthier choices ( EC 2018 , GBD 2015 , WHO 2007b  ).

Many countries have also action plans and strategies to specifically tackle childhood obesity ( OECD 2019 , EC 2018 , World Obesity 2019 (pdf)  ). The Commission on Ending Childhood Obesity identifies three critical periods during the life course where consideration should be taken for preventing obesity: preconception and pregnancy, infancy and early childhood, and older childhood and adolescence ( WHO 2016 ). The EU Action Plan on Childhood Obesity 2014-2020 provides guidance to Member States by outlining several key areas of action, including supporting a healthy start in life; promoting healthier environments, especially in schools and pre-schools; making the healthy option the easier option; restricting marketing and advertising to children; and encouraging physical activity ( EC 2014 (pdf)  ). The mid-term evaluation of the EU Action Plan showed that all countries were active in more than one of the areas for action with a number of countries moving from having plans to implementation ( EC 2018 ). Moreover, a study evaluating the EU Action Plan was launched in September 2023 to examine progress from Member States in addressing the Action Plan key areas, by mapping ongoing and planned initiatives, remaining challenges and implemented best practices. Findings are to be published in 2025, informing on possible future actions to address childhood obesity.

Several EU initiatives, such as Europe's Beating Cancer Plan or the EU NCD Initiative , have prioritised actions relevant to childhood obesity such as: setting targets for food reformulation; reducing aggressive online and TV marketing to children and teenagers; and making healthy products more available to children through the EU school fruit, vegetables and milk scheme or by revising public procurement guidelines for purchasing food. In addition, through different funding mechanisms, the EU is co-financing projects that contribute to EU policy aims ( CORDIS ). It also supports Member States in their efforts to implement relevant policies at a national level through Joint Actions such as Best-ReMaP and Prevent NCD.

At a wider European or global level, organisations, such as the WHO, the WHO Regional Office for Europe or UNICEF, have developed resources that support countries in developing and implementing policies for the prevention of childhood overweight and obesity ( WHO Europe 2023 , WHO Europe 2022 , WHO Europe , UNICEF 2021 , WHA 2022 (pdf)  , WHO 2023d  ). 

Primary Prevention programmes and policy recommendations related to the consumption of fats, fruit and vegetables, sugars and sweeteners, whole grain, as well as to physical activity and sedentary behaviour and food and non-alcoholic beverage marketing to children and adolescents are listed in the relevant chapters of this Health Promotion and Disease Prevention Knowledge Gateway.

Best practices of obesity prevention in childhood can be obtained from the repository of the Best Practice Portal of the European Commission.
 

References

Overview of the references to this brief