Body mass index of children and youth, 2012 to 2013

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Children and youth who are overweight or obese are at increased risk of remaining obese throughout adulthood.Note 1 Further, overweight or obese children and youth are at present and future risk of adverse health consequences including cardiovascular disease, type 2 diabetes and many cancers (i.e. colorectal, kidney and oesophageal cancer).Note 1,Note 2 Overweight or obese children and youth are also more likely to have a reduced quality of life and are at a greater risk of being teased, bullied and socially isolated.Note 2

In 2012 to 2013, 31% of children and youth 5 to 17 years were overweight and obese, based on the body mass index (BMI) measured as part of the Canadian Health Measures Survey (CHMS). The prevalence of overweight and obesity differed by age group. Children and youth aged 12 to 17 (37%) were more likely to be overweight or obese than those aged 5 to 11 (26%) (data not shown).

Chart 1  Distribution of boys aged 5 to 17, by body mass index (BMI)1 and age group, household population, Canada, 2012 to 2013

Description for chart 1

Boys (15%) were more likely to be obese than girls (11%); however boys and girls were equally likely to be overweight (19%) (Charts 1 and 2). Boys aged 12 to 17 were more likely to be overweight (23%) or obese (21%) compared to boys aged 5 to 11 where 14% were overweight and 8% were obese. Among girls, there were no significant differences in weight classification across age groups. For girls aged 5 to 11, 19% were overweight and 9% were obese. For girls aged 12 to 17, 18% were overweight and 12% were obese.

Chart Distribution of girls aged 5 to 17, by age group and body mass index (BMI),1 household population, Canada, 2012 to 2013

Description for chart 2

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About body mass index

Body mass index (BMI) is the ratio of a person’s weight in kilograms divided by their height squared in meters (kg/m2). BMI represents an estimate of adipose or fatty tissue based on weight related to height and its accuracy increases with the degree of body fatness.Note 1 It is important to note that the BMI does not directly measure body fat and can lead to some measurement and misclassification as a higher BMI can be a result of increased levels of fat-free mass (e.g., muscle, bone).Note 1 For example, a person with greater fat-free mass (e.g. muscle or bone)Note 1 might be categorized as overweight based on their BMI, but the actual health risk for that person would be lower than someone with the same BMI who has more fat mass.

BMI classification of children and youth can be done using various systems; the World Health Organization’s BMI-for-age Growth References is the current preferred classification system and is used to represent the current findings.

This classification system uses the following cut-offs: Note 3

Table summary
This table displays the results of Title. The information is grouped by Cut-off (appearing as row headers), Category (appearing as column headers).
Cut-off Category
Less than or equal to 2 standard deviations below the mean Thinness
Greater than 2 standard deviations below the mean and less than or equal to 1 standard deviation above the mean Normal weight
Greater than 1 standard deviation and less than or equal to 2 standard deviations above the mean Overweight
Greater than 2 standard deviations above the mean Obesity

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de Onis, M., Onyango, A.W., Borghi, E., Siyam, A., Nishida, C., and J. Siekmann. 2007. “Development of a WHO growth reference for school-aged children and adolescents.” Bulletin of the World Health Organization Vol. 85, no. 9.

Ontario Agency for Health Protection and Promotion (Public Health Ontario). 2013. Addressing Obesity in Children and Youth: Evidence to Guide Action for Ontario.
(accessed: May 2014).

World Health Organization (WHO) 2012. Population-based Approaches to Childhood Obesity Prevention.
(accessed: May 2014).


Additional data from the Canadian Health Measures Survey are available from CANSIM tables 117-0001 to 117-0011.

For more information on the Canadian Health Measures Survey, please contact Statistics Canada's Statistical Information Service (toll-free 1-800-263-1136; 514-283-8300;

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