NCHS Data Brief ■ No. 56 ■ March 2011

Adult Obesity Prevalence in Canada and the United States

Margot Shields; Margaret D. Carroll, M.S.P.H.; and Cynthia L. Ogden, Ph.D.

Obesity is a public health challenge throughout the world (1). Ongoing 

monitoring of trends in obesity is important to assess interventions aimed 

at preventing or reducing the burden of obesity. Since the 1960s, measured 

height and weight have been collected in the United States as part of the 

National Health and Nutrition Examination Survey (NHANES). In Canada, 

data on measured height and weight have been collected from nationally 

representative samples of the population less regularly. This changed in 2007 

with the launch of the Canadian Health Measures Survey (CHMS), the scope 

and purpose of which are similar to those of NHANES. The objective of this 

report is to compare estimates of the prevalence of obesity between Canadian 

and American adults.

Keywords: National Health and Nutrition Examination Survey • Canadian 

Health Measures Survey • body mass index • international comparison

Are there differences in obesity prevalence estimates 

between Canada and the United States?

In 2007–2009, the prevalence of obesity in Canada was 24.1%, over 10 

percentage points lower than in the United States (34.4%). Among men, the 

u.s. department of health and human services

centers for disease control and prevention

national center for health statistics

Key findings

Data from the Canadian 

Health Measures Survey, 

2007–2009; the Canadian 

Heart Health Surveys, 

1986–1992; and the 

U.S. National Health and 

Nutrition Examination 

Survey, 1988–1994 and 

2007–2008

•	 The prevalence of obesity 

among adults in Canada is 

lower than it is in the 

United States.

•	 Among the non-Hispanic 

white population, the 

prevalence of obesity is 

lower in Canada than in 

the United States, but the 

difference is not as large as it 

is when comparing the entire 

populations.

•	 Between the late 1980s and 

2007–2009, the prevalence 

of obesity increased in both 

Canada and the United States.

•	 In 2007–2009, the 

prevalence of obesity among 

young and middle-aged 

Canadian women was similar 

to that observed in U.S. 

women 20 years earlier.

1

Significantly different from estimate for Canada (p < 0.05). 2

Use with caution (coefficient of variation 16.6%–33.3%).

NOTES: BMI is body mass index. Estimates were age-standardized by the direct method to the 2000 United States Census 

population using age groups 20–39, 40–59, and 60–79. Pregnant women are excluded. Obesity class estimates do not sum to 

exact totals due to rounding.

SOURCES: CDC/NCHS, 2007–2008 National Health and Nutrition Examination Survey and 2007–2009 Canadian Health 

Measures Survey.

Figure 1. Prevalence of obesity in those aged 20–79, by sex: Canada, 2007–2009 and 

United States, 2007–2008

0

5

10

15

20

25

30

35

40

Percent

24.1

15.1

5.8

3.1

17.6

4.5

2.2

12.7

7.2

2

4.0

1

34.4

1

19.6

1

8.8

1

6.0

1

21.7

1

6.6

1

4.3

1

17.7

1

11.0

1

7.6

24.3

1

32.6

23.9

1

36.2

Women

Canada United

States

Men

Canada United

States

Total

Canada United

States

Obesity class I

(BMI 30.0–34.9)

Obesity class II

(BMI 35.0–39.9)

Obesity class III

(BMI 40.0 or higher)
NCHS Data Brief ■ No. 56 ■ March 2011

■  2  ■

prevalence of obesity was over 8 percentage points lower in Canada than in the United States 

(24.3% compared with 32.6%) and among women, more than 12 percentage points lower (23.9% 

compared with 36.2%) (Figure 1). 

Because the risk of adverse health effects increases at higher levels of body mass index (BMI), 

obesity is divided into three categories (1,2). In all three categories, prevalence was significantly

lower in Canada than in the United States. In the highest BMI category the prevalence was twice 

as high in the United States (6.0%) compared with Canada (3.1%).

Are there differences in obesity prevalence estimates between the 

non-Hispanic white populations in Canada and the United States?

When comparisons were restricted to the non-Hispanic white population in each country, 

differences in obesity estimates were somewhat attenuated but the overall prevalence of obesity 

remained significantly lower in Canada than in the United States among both men and women

(Figure 2).

Figure 2. Prevalence of obesity in the non-Hispanic white population aged 20–79, by sex: Canada, 2007–2009 and 

United States, 2007–2008 

1

Significantly different from estimate for Canada (p < 0.05). 2

Use with caution (coefficient of variation 16.6%–33.3%).

NOTES: BMI is body mass index. Estimates were age-standardized by the direct method to the 2000 United States Census population using age groups 20–39, 

40–59, and 60–79. Pregnant women are excluded.

SOURCES: CDC/NCHS, 2007–2008 National Health and Nutrition Examination Survey and 2007–2009 Canadian Health Measures Survey.

0

5

10

15

20

25

30

35

40

Percent

25.6

15.9

6.2

3.5

18.7

5.4

2

2.7

13.1

7.0

2

4.4

1

33.0

1

19.0

1

8.6

5.4

21.8

6.6

4.1

1

16.3

1

10.7

6.7

26.8

1

32.5

24.5

1

33.7

Women

Canada United

States

Men

Canada United

States

Total

Canada United

States

Obesity class I

(BMI 30.0–34.9)

Obesity class II

(BMI 35.0–39.9)

Obesity class III

(BMI 40.0 or higher)

In Canada, almost 26% of the non-Hispanic white population was obese compared with 33.0% of 

the non-Hispanic white population in the United States. Among the heaviest (class III obesity), 

however, the prevalence was more similar in the two countries (3.5% in Canada and about 5% in 

the United States).
NCHS Data Brief ■ No. 56 ■ March 2011

■  3  ■

The racial makeup of the population in the two countries explains why the difference in 

prevalence is larger when the general populations are compared than when the non-Hispanic white 

populations are compared. In the United States, the majority of the nonwhite population is black 

or Hispanic for whom the prevalence of obesity is higher than it is for the white population (3). 

Among nonwhite Canadians, the largest group is comprised of East/Southeast Asian persons for 

whom the prevalence of obesity is lower than it is for the white population (4). 

Have changes in obesity prevalence in the last 20 years been similar in 

Canada and the United States?

Current obesity prevalence estimates were compared with estimates from the 1988–1994 

NHANES and the 1986–1992 Canadian Heart Health Surveys (CHHS). In both countries the 

prevalence of obesity rose significantly since these earlier surveys, and the magnitude of the

increases were fairly similar in the two countries. In Canadian men the prevalence rose by 

approximately 10 percentage points, and among men in the United States the prevalence rose by 

12 percentage points (Figure 3). Among women, the increase was approximately 8 percentage 

points in Canada and approximately 10 percentage points in the United States (Figure 4).

1

Significantly different from 0 (p < 0.05). 2

Estimate age-standardized by the direct method to the 2000 United States Census population using age groups 20–39, 40–59, and 60–74. 

NOTE: Estimates do not sum to exact totals due to rounding.

SOURCES: CDC/NCHS, National Health and Nutrition Examination Surveys, 2007–2009 Canadian Health Measures Survey, and 1986–1992 Canadian Heart 

Health Surveys.

Figure 3. Prevalence of obesity in men aged 20–74, by age group: Canada, 1986–1992 and 2007–2009 and 

United States, 1988–1994 and 2007–2008

0

10

20

30

40

50

Percent

24.3

1

10.3

14.0

32.5

1

12.0

20.5

18.9

1

9.4

9.5

27.4

1

12.6

14.8

26.9

1

8.6

18.3

34.2

1

8.8

25.4

31.9

1

17.0

15.0

41.8

1

18.1

23.7

Age group in years

2

20–74

Canada United

States

20–39

Canada United

States

40–59

Canada United

States

60–74

Canada United

States

Percentage-point

increase:

Canada, 

1986–1992 to 

2007–2009

United States, 

1988–1994 to 

2007–2008

Canada, 

1986–1992

United States, 

1988–1994

Over the 20-year period, patterns of increase were fairly consistent across age groups, in both the 

United States and Canada. Among men, the increase was highest among those aged 60–74: 

17 percentage points in Canada and approximately 18 percentage points in the United States. 

Among women, the increases were highest among those aged 20–39. In Canada the prevalence 

increased over 11 percentage points and in the United States over 13 percentage points. 
NCHS Data Brief ■ No. 56 ■ March 2011

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At both time points, significant differences in prevalence estimates between the two countries

were pronounced for young (those aged 20–39) and middle-aged (those aged 40–59) women. In 

these age groups, the prevalence of obesity in Canadian women in 2007–2009 was similar to or 

lower than that observed in U.S. women 20 years earlier (Figure 4). Among older women, obesity 

prevalence estimates were similar between the two countries and differences were not statistically 

significant at either time period.

1

Significantly different from 0 (p < 0.05). 2

Estimate age-standardized by the direct method to the 2000 United States Census population using age groups 20–39, 40–59, and 60–74. 

NOTE: Pregnant women are excluded.

SOURCES: CDC/NCHS, National Health and Nutrition Examination Surveys, 2007–2009 Canadian Health Measures Survey, and 1986–1992 Canadian Heart 

Health Surveys.

Figure 4. Prevalence of obesity in women aged 20–74, by age group: Canada, 1986–1992 and 2007–2009 and 

United States, 1988–1994 and 2007–2008

0

10

20

30

40

50

Percent

23.8

1

8.2

15.6

36.2

1

10.3

25.9

20.8

1

11.5

9.3

34.0

1

13.3

20.7

23.9

5.0

18.9

38.1

1

7.8

30.3

31.5

7.4

24.1

36.9

1

8.4

28.5

United

States

Age group in years

2

20–74

Canada

20–39

Canada United

States

40–59

Canada United

States

60–74

Canada United

States

Percentage-point

increase:

Canada, 

1986–1992 to 

2007–2009

United States, 

1988–1994 to 

2007–2008

Canada, 

1986–1992

United States, 

1988–1994
NCHS Data Brief ■ No. 56 ■ March 2011

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Summary

The prevalence of obesity is significantly higher among U.S. adults than among their Canadian

counterparts. U.S. estimates were higher for all three obesity classes for both men and women. 

When the population was limited to non-Hispanic white persons, the overall prevalence of obesity 

for both U.S. men and women remained statistically higher than those for Canadian men and 

women, but the magnitude of the difference was reduced and there was no significant difference

in the prevalence of class III obesity.

Between the late 1980s and today, the prevalence of obesity increased significantly in both the

United States and Canada. Increases followed a similar pattern in the two countries, particularly 

among men. Among women, increases have also occurred in both countries; however, in both the 

late 1980s and today the estimates of obesity prevalence for young and middle-aged U.S. women 

have been substantially higher than for their Canadian counterparts. In the United States the 

increases in the prevalence of obesity observed in the 1980s and 1990s did not appear to continue 

at the same rate during the current decade, particularly among women and possibly for men (3). 

Insufficient data points for measured height and weight preclude the possibility of conducting

a similar study on the Canadian population. However, the availability of future cycles of 

NHANES and CHMS data will permit further exploration and comparison of obesity trends in 

the two countries.

Definitions

Body mass index (BMI): Calculated as weight in kilograms (kg) divided by height in meters 

squared (m2

), rounded to one decimal place. For male and female adults aged 20 and over, 

obesity class I was defined as a BMI of 30.0–34.9 kg/m2; obesity class II was defined as a

BMI of 35.0–39.9 kg/m2

; and obesity class III was defined as a BMI of 40.0 kg/m2 or higher. 

See the Table below for examples of obesity at different heights.

Table. Obesity cut points for adults 5’4” and 5’9”

Height Obesity class I Obesity class II Obesity class III

5’4” 174 pounds 204 pounds 232 pounds

5’4” 79 kilograms 93 kilograms 105 kilograms

5’9” 203 pounds 236 pounds 270 pounds

5’9” 92 kilograms 107 kilograms 123 kilograms

Data sources

U.S. estimates were based on data from two surveys that are part of NHANES (5)—the third 

NHANES (NHANES III) and NHANES 2007–2008. NHANES is designed to monitor the health 

and nutritional status of the U.S. civilian noninstitutionalized population. The survey consists of 

interviews conducted in participants’ homes, standardized physical examinations conducted in 

mobile examination centers, and laboratory tests utilizing blood and urine specimens provided by 

participants during the physical examination.

NHANES III, the third in a series of periodic NHANES surveys, was conducted during 

1988–1994. Beginning in 1999, NHANES became a continuous survey, fielded on an ongoing

basis. Public-use data files are released in 2-year cycles. Each 2-year cycle of data collection is

based on a representative sample covering all ages of the civilian noninstitutionalized population.
NCHS Data Brief ■ No. 56 ■ March 2011

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NHANES III and NHANES 2007–2008 samples were selected through a complex multistage 

design that includes selection of primary sampling units (counties), segments (groups of 

households) within the counties, households within segments, and finally, sample persons within

households. The sample design includes oversampling in order to obtain reliable estimates of 

health and nutritional measures for population subgroups. In 2007–2008, African-American 

persons, all Hispanic persons, persons with low income, and persons aged 60 and over were 

oversampled. In NHANES III, children aged 2 months–5 years, older persons aged 60 and over, 

non-Hispanic black persons, and Mexican-American persons were oversampled. In 2007–2008, 

measured height and weight were collected from 5,181 NHANES respondents aged 20–79 and 

4,876 aged 20–74. During NHANES III, measured height and weight were collected from 14,319 

adults aged 20–74.

Canadian estimates are based on data from cycle 1 of CHMS collected between March 2007 

and February 2009 (6). CHMS covered the population aged 6–79 living in private households. 

Residents of Indian Reserves or Crown lands, institutions and certain remote regions, and 

full-time members of the regular Canadian Forces were excluded. Approximately 96.3% of 

Canadians were represented. In addition to a household interview, CHMS involved a visit to 

a mobile examination center where respondents underwent anthropometric measurements, 

participated in fitness tests, and blood and urine specimens were taken.

Sample selection for CHMS was based on the Canadian Labour Force Survey area frame, which 

was used to create 257 sites across the country grouped into four strata (7). A total of 15 sites 

were selected at random from the four strata using a systematic sampling method with probability 

proportional to the size of each site’s population. Further stratification was carried out within each

sampled site and a random sample of dwellings was selected from each stratum. Finally, one or 

two persons were selected at random within each sampled dwelling. In the 2007–2009 CHMS, 

measured height and weight were collected from 3,486 respondents aged 20–79.

Historical estimates in Canada are from CHHS, conducted between 1986 and 1992. Respondents 

were sampled through a stratified multistage probability sampling design (8). The medical

insurance registers of the 10 provinces were used as the sampling frame from which age-sex 

strata were formed and a sample of persons was selected at random from each stratum. Measured 

height and weight were obtained for 19,208 respondents aged 20–74. Comparisons of the 

prevalence of obesity over time were based on the population aged 20–74 because CHHS did not 

include those aged 75 and over.

For all surveys, sample weights—which account for the differential probabilities of selection, 

nonresponse, and noncoverage—are incorporated into the estimation process. The total estimates 

were age-adjusted by the direct method to the 2000 United States Census population using 

three age groups: 20–39, 40–59, and 60–79 (or 20–39, 40–59, and 60–74 for analyses across 

time). Estimates age standardized to the Canadian population were almost identical to estimates 

standardized to the U.S. population. To compare the prevalence of obesity between the United 

States and Canada, statistical hypotheses were tested using a Student’s t statistic with 11 degrees 

of freedom and an α level of 0.05. All data analyses were performed using the statistical packages 

SAS version 9.21 (SAS Institute, Cary, N.C.) and SUDAAN version 10 (Research Triangle 

Institute, Research Triangle Park, N.C.). 
NCHS Data Brief ■ No. 56 ■ March 2011

■  7  ■

About the authors

Margot Shields is with Statistics Canada, Health Analysis Division. Margaret D. Carroll and 

Cynthia L. Ogden are with the Centers for Disease Control and Prevention’s National Center for 

Health Statistics, Division of Health and Nutrition Examination Surveys.

References

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2. Health Canada. Canadian guidelines for body weight classification in adults. Catalogue

H49–179/2003E. Ottawa: Health Canada. 2003.

3. Flegal KM, Carroll MD, Ogden CL, Curtin LR. Prevalence and trends in obesity among US 

adults, 1999–2008. JAMA 303(3):235–41. 2010.

4. Tremblay MS, Pérez CE, Ardern CI, Bryan SN, Katzmarzyk PT. Obesity, overweight and 

ethnicity. Statistics Canada, Catalogue 82–003. Health Rep 16(4):23–34. 2005.

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Available from: http://www.cdc.gov/nchs/nhanes/nhanes_questionnaires.htm [Accessed 7/18/10]. 

6. Tremblay M, Wolfson M, Connor Gorber S. Canadian Health Measures Survey: Rationale, 

background and overview. Statistics Canada, Catalogue 82–003. Health Rep 18 Suppl:7–20. 2007.

7. Giroux S. Canadian Health Measures Survey: Sampling strategy overview. Statistics Canada, 

Catalogue 82–003. Health Rep 18 Suppl:31–6. 2007.

8. MacLean DR, Petrasovits A, Nargundkar M, Connelly PW, MacLeod E, Edwards A, Hessel 

P. Canadian Heart Health Surveys: A profile of cardiovascular risk. Survey methods and data

analysis. Canadian Heart Health Surveys Research Group. CMAJ 146(11):1969–74. 1992.
NCHS Data Brief ■ No. 56 ■ March 2011

Suggested citation

Shields M, Carroll MD, Ogden CL. 

Adult obesity prevalence in Canada and 

the United States. NCHS data brief, no 56. 

Hyattsville, MD: National Center for 

Health Statistics. 2011.

Copyright information

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the public domain and may be reproduced 

or copied without permission; citation as to 

source, however, is appreciated.

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Statistics

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Jennifer H. Madans, Ph.D., Associate 

 Director for Science

Division of Health and Nutrition 

Examination Surveys

Clifford L. Johnson, M.S.P.H., Director

U.S. Department of

Health & Human Services

Centers for Disease Control and Prevention

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