Children who are overweight or obese
are at greater risk of poor health, both in adolescence and in adulthood. Being overweight
in childhood increases the risk of developing cardiovascular disease or diabetes, as well
as related social and mental health problems. Excess weight problems in childhood are
associated with an increased risk of being an obese adult, at which point certain forms of
cardiovascular diseases, cancer, osteoarthritis, a reduced quality of life and premature
death can be added to the list of health concerns (Sassi, 2010).
Evidence suggests that even if excess
childhood weight is lost, adults who were obese children retain an increased risk of
cardiovascular problems. And although dieting or increased physical activity can combat
obesity, children are at a greater risk of again putting on weight when they revert to
previous lifestyles. In addition, dieting may lead to eating disorders, symptoms of stress
and postponed physical development.
Figure 2.4.1 shows estimates by the International Association for the Study
of Obesity of the prevalence of overweight (including obesity) in OECD and emerging
countries among school-aged children aged 5-17 years, based on latest available national
studies which measure height and weight, and using IASO definitions of overweight/obesity.
One-in-five children are affected by excess body weight across all countries, and in
Greece, the United States and Italy the figure is closer to one third. Only in China,
Korea and Turkey are 10% or less of children overweight. In most countries, boys have
higher rates of overweight and obesity than do girls. Girls tend to have higher rates in
Nordic countries (Sweden, Norway, Denmark), as well as in the United Kingdom, the
Netherlands and Australia.
Many countries recognise the need for
standardised and harmonised surveillance systems on which to base policy development to
address overweight and obesity among children. In response to this need, the WHO European
Childhood Obesity Surveillance Initiative (COSI) aims to routinely measure trends in
overweight and obesity in primary-school children. Figure 2.4.2 presents the proportion of overweight (including obese) for 6-
to 9-year-old children, as measured during the first COSI data collection round undertaken
in 2007-08. Prevalence estimates were based on the 2007 WHO recommended growth reference
for school-aged children and adolescents (de Onis et al., 2007). There are important differences among children with excess
weight problems, not only across countries, but also according to their age. In general,
older children have more excess weight than younger children.
Rates of overweight among boys and
girls are increasing across the OECD. In many developed countries, child obesity levels
doubled between the 1960s and 1980s, and have doubled again since then. Even in emerging
countries, the prevalence of obesity is rising, especially in urban areas where there is
more sedentary behaviour and a greater access to energy-dense foods (Sassi, 2010).
Childhood is an important period for
forming healthy behaviours. The school environment provides an opportunity to ensure that
children understand the importance of good nutrition and physical activity, and can
benefit from both. Studies show that locally focussed actions and interventions,
especially those targeting 5-12 year-olds, can be effective in changing behaviours (Sassi,
Definition and comparability
Estimates of the prevalence of
child overweight were made by the International Association for the Study of Obesity
(IASO). The estimates are based on national surveys of measured height and weight
among children. Definitions of overweight and obesity among children may sometimes
vary among countries, although wherever possible IASO age- and sex-specific cut-off
points were used (Cole et al., 2000). Calculated
for ages 2 to 18, these cut-off points can be used for different ethnicities, and also
link to widely-used adult cut-off points.
For the WHO European Childhood
Obesity Surveillance Initiative (COSI), trained examiners took anthropometric
measurements which were standardised according to a common protocol. Overweight was
defined as the proportion of children with BMI-for-age values greater than one
standard deviation, based on WHO recommended cut-offs for school-age children and
adolescents (de Onis et al., 2007). Body weight was
adjusted for the clothes worn when measured, and extreme values (less than or greater
than five standard deviations) were excluded from calculations.
Indicator in PDF
2.4.1 Children aged 5-17 years who are overweight (including
obese), latest available estimates
2.4.2 Prevalence of overweight (including obesity) among 6-
to 9-year-old children in eight OECD countries, 2007-08