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Overweight and obesity in adolescents (Indicator 13)

Published Updated


The indicator describes the following: Prevalence of overweight and obesity in adolescents.


This indicator is part of Target (7): Halt the rise in diabetes and obesity.

The indicator is based on measured height and weight among a representative sample of children and adolescents taken from the general population.

Results

During the period 2005-2018, the proportion of 8 and 9-year-olds with overweight and obesity has remained relatively stable, at under 20 per cent for boys and about 20 per cent among girls. The proportion of  individuals with obesity has also remained stable at between 2 and 6 per cent. This is shown by figures from the Child Growth Study (Figure 1) and from the national mapping studies of physical activity, ungKan1, ungKan2 and ungKan3 (Figure 2). 

During the period 2005/06 to 2011/12, the proportion of 15-year-olds with overweight and obesity increased, an increase that has held relatively stable between 2011 and 2018. Among 15-year-old boys, the proportion with overweight or obesity has remained relatively stable between 2005/06 and 2018, and the proportion of 15-year-old boys with obesity declined from 4 per cent in 2005 to 2 % in 2018.  This means that the increase in proportion of 15-year-olds with overweight or obesity is mainly driven by changes among girls. In 2005/06, the proportion of 15-year-old girls with overweight or obesity was approximately 16 per cent, whereas in 2018 it was approximately 21%. Over the same time period, the proportion of 15-year-old girls with obesity has more than doubled, from about 2 per cent in 2005/06 to about 5 % in 2018.   

This is shown by figures from the National Mapping Studies on Physical Activity, ungKan1, ungKan2 and ungKan3 (Figure 3).

NCD 13 Fig 1 overvekt og fedme ENG.jpg

Figure 1: Proportion of boys and girls aged 8-9 years with overweight and obesity during the period 2008-2015, as a percentage. Source: The Child Growth Study, Norwegian Institute of Public Health. See Table 1 below. 

NCD 13 Fig 2 overvekt og fedme ENG.jpg

Figure 2Percentage of nine-year-old girls and boys with overweight and obesity in 2005/06, 2011/12 and 2018. Source: National Mapping Study on Physical Activity, Norwegian School of Sport Sciences, Norwegian Directorate of Health and Norwegian Institute of Public Health.  See Table 2 below. 

NCD 13 Fig 3 overvekt og fedme ENG.jpg

Figure 3: Proportion of 15-year-old girls and boys with overweight and obesity in 2005/06, 2011/12 and 2018, as a percentage. Source: National Mapping Study on Physical Activity, Norwegian School of Sport Sciences, Norwegian Directorate of Health and Norwegian Institute of Public Health. See Table 3 below. 

Data sources

The data source for this indicator is Child Growth Study (8-9 year-olds) and the National Mapping Study on Physical Activity among Nine and Fifteen-year-olds (ungKan).

A description and definitions follow below.

Data source: Child Growth Study

Description 

The Child Growth Study took the height, weight and waist circumference measurements of a nationally representative sample of primary 3 pupils (8-9 year olds). The study was conducted in 2008, 2010, 2012 and 2015 in collaboration with the School Health Service and the Norwegian Directorate of Health under the direction of the Norwegian Institute of Public Health. 

Effect measure

  • Proportion of children with overweight (not obesity) among 8-9 year olds, as a percentage.
  • Proportion of 8-9 year olds with obesity, as a percentage.
  • Proportion of children aged 8-9 with overweight and obesity, as a percentage. 

The data are based on physical measurements, and the threshold values of the International Obesity Task Force (IOTF) are used to classify overweight and obesity, also known as the Cole Index (Cole TJ, BMJ 2000).

IOTF’s threshold values classify overweight and obesity based on body mass index (BMI). BMI thresholds for overweight and obesity are not the same for children as for adults. Children are differently proportioned, so threshold values must be based on the actual build of children at a given age. IOTF’s threshold values for children and adolescents are provided for boys and girls at half-year cut-off points between two and 18 years of age. An international expert group has been set up based on six major international cross-sectional studies from Brazil, the UK, Hong Kong, the Netherlands, Singapore and the US (Cole TJ, BMJ 2000). 

Data quality

Statistics Norway (SSB) selected schools in such a way as to render the sample representative on both a national and a health region level. The participation rate among pupils was high, totalling 89 per cent in both 2008 and 2010. Only one per cent actively declined to allow their children to take part. The other 10 per cent who did not participate were absent on the day of measurement (due to illness, travel, etc). 

The pupils were individually weighed and measured, wearing light clothing, at the School Health Service office. The tables of results are adjusted for clothing. 

Interpretation and sources of error

The Child Growth Study forms part of the monitoring programme the WHO European Childhood Obesity Surveillance Initiative (COSI), which enables comparisons of results among several European countries.

Reference:

Cole TJ, Bellizzi MC, Flegal KM et al. Establishing a standard definition for child overweight and obesity worldwide: international survey. BMJ. 2000;320(7244):1240-1243. 

Data source: National Mapping Study on Physical Activity ungKan

Description 

Physical activity among nine and 15-year-olds in Norway (UngKan) was mapped at national level in 2005-2006 (89 and 74 per cent participation), 2011 (55 and 73 per cent participation) and 2018 (73 and 57 per cent participation). Mapping also included height and weight measurement.  The studies were conducted by the Norwegian School of Sport Sciences and commissioned by the Norwegian Directorate of Health.

Effect measure

  • Proportion of 9-year-olds with overweight (not obesity), as a percentage.
  • Proportion 9-year-olds with obesity, as a percentage.
  • Proportion of 9-year-olds with overweight and obesity, as a percentage. 
  • Proportion of 15-year-olds with overweight (not obesity), as a percentage.
  • Proportion of 15-year-olds with obesity, as a percentage.
  • Proportion of 15-year-olds with overweight and obesity, as a percentage. 

The data are based on physical measurements, and the threshold values of the International Obesity Task Force (IOTF) are used to classify overweight and obesity, also known as the Cole Index (Cole TJ, BMJ 2000) 

Overweight and obesity are classified based on body mass index (BMI). BMI thresholds for overweight and obesity are not the same for children as for adults. Children are differently proportioned, so threshold values must be based on the actual build of children at different ages. IOTF’s threshold values for children and adolescents are provided for boys and girls at half-year cut-off points between two and 18 years of age. They have been developed by an international expert group from IOTF and are based on six major international cross-sectional studies from Brazil, the UK, Hong Kong, the Netherlands, Singapore and the US (Cole TJ, BMJ 2000). 

Interpretation and sources of error

The estimated prevalence of overweight and obesity is influenced by the sample being studied. For children and adolescents, the prevalence data may also vary depending on the threshold values used to classify overweight and obesity. In the UngKan studies, the threshold values of the Cole Index were chosen (Cole TJ, BMJ 2000) since these are standardised in respect of age and gender and directly comparable to the threshold values for overweight (BMI 25-30) and obesity (BMI>30) in adults. Where other threshold values are used, e.g. those of Onis et al (de Onis M. Bull World Health Organ. 2007), the prevalence data will change.

In the UngKan studies, the measurement of height and weight followed the same clinical standards on both measurement dates. The BMI values from 2005/06, 2011/12 and 2018 are therefore valid, and future measurements will be easily reproducible.  

References

Cole TJ, Bellizzi MC, Flegal KM et al. Establishing a standard definition for child overweight and obesity worldwide: international survey. BMJ. 2000;320(7244):1240-1243. 

de Onis M et al. Development of a WHO growth reference for school-aged children and adolescents. Bull World Health Organ. 2007 Sep;85(9):660-7

Data quality

Schools across the entire country were selected for the UngKan studies and invited to participate by Statistics Norway (SSB). Selection took into consideration geography and population density, which ensured that the invited nine and 15-year-olds constituted a representative sample of Norwegian nine and 15-year-olds. The proportion of those invited who agreed to participate was high in both studies. In 2005/06, 89 per cent of nine-year-olds and 74 per cent of 15-year-olds agreed to participate. In 2011/12, the corresponding participation rates were 73 per cent and 63 per cent. 

Tables accompanying the figures 

 

2008

2010

2012

2015

Boys

 

 

 

 

Overweight

11

12

11

11

Obesity

3

4

3

2

Overweight and obesity

14

16

14

13

Girls

 

 

 

 

Overweight

13

17

13

14

Obesity

4

3

4

3

Overweight and obesity

16

20

18

17

Both genders together

 

 

 

 

Overweight

12

14

12

12

Obesity

3

4

4

3

Overweight and obesity

15

18

16

15

Table 1: Proportion of overweight and obese children among boys, girls and both genders together, aged 8-9 years during the period 2008-2015, as a percentage. Source: Child Growth Study, Norwegian Institute of Public Health. 

 

2005/06

2011

2018

Boys

 

 

 

Overweight

13

13

17

Obesity

4

6

3

Overweight and obesity

16

19

20

Girls

 

 

 

Overweight

15

19

19

Obesity

5

4

3

Overweight and obesity

20

23

23

Both genders

 

 

 

Overweight

14

16

18

Obesity

4

5

3

Overweight and obesity

18

21

21

Table 2: Proportion of 9-year-old girls and boys with overweight and obesity in 2005-06, 2011 and 2018 as a percentage. Source: National Mapping Study on Physical Activity, Norwegian School of Sport Sciences, Norwegian Directorate of Health and Norwegian Institute of Public Health.  

 

2005/06

2011

2018

Boys

 

 

 

Overweight

7

12

11

Obesity

4

3

2

Overweight and obesity

11

14

13

Girls

 

 

 

Overweight

15

19

17

Obesity

2

3

5

Overweight and obesity

16

23

21

Both genders

 

 

 

Overweight

11

15

14

Obesity

3

3

3

Overweight and obesity

14

18

17

Table 3: Proportion of 15-year-old girls and boys with overweight and obesity in 2005-06, 2011 and 2018 as a percentage. Source: National Mapping Study on Physical Activity, Norwegian School of Sport Sciences, Norwegian Directorate of Health and Norwegian Institute of Public Health.  

National adaptation to global indicators 

WHO’s definition of the indicator

Indicator 13. Prevalence of overweight and obesity in adolescents (defined according to the WHO growth reference for school-aged children and adolescents, overweight – one standard deviation body mass index for age and sex, and obese – two standard deviations body mass index for age and sex). 

National adaptation

Age and gender-specific BMI threshold values were used. These threshold values are based on six studies which taken together include >190 000 children and adolescents, where the standardised threshold values for overweight and obesity are equivalent to adult BMI values of 25-30 (overweight) and >30 (obesity). WHO’s definition was not used (de Onis Bull World Health Organ. 2007).