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Review
The Public Health Burden of Obesity in Canada
Ian Janssen PhD *
School of Kinesiology and Health Studies and Department of Community Health and Epidemiology, Queen’s University, Kingston, Ontario, Canada
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 26 November 2012
Received in revised form
31 January 2013
Accepted 21 February 2013
The purpose of this review was to provide an overview of the public health burden of obesity in Canada.
Based on nationally representative surveys that obtained measured heights and weights and that defined
obesity using a body mass index (BMI) cutpoint of 30 kg/m2, the prevalence of obesity in Canadian adults
increased from 10% in 1970/72 to 26% in 2009/11. The prevalence of obesity in children has tripled since 1981,
and based on the World Health Organization BMI growth standards, 12% of Canadian school-aged children
were obese in 2009/11. At present, there are approximately 7 million obese adults and 600 000 obese schoolaged children in Canada. Prevalence estimates based on waist circumference are even more troubling as they
indicate that 37% of adults and 13% of youth are abdominally obese. Obesity is a major contributor to
morbidity and mortality in the Canadian population. For instance, 61% to 74% of type 2 diabetes cases, 17% to
32% of osteoarthritis cases, 14% to 21% of colorectal cancers, 8% to 14% of depression cases, and 20% of
premature deaths that occur in Canadian adults are estimated to be directly attributable to obesity. Obesity
also places a large economic burden on the country. In 2006 obesity accounted for $3.9 billion in direct
health care costs (e.g., hospitalizations, medications, physician and emergency room visits) and $3.2 billion
in indirect costs (e.g., costs related to disability and lost productivity due to illness or premature death).
Ó 2013 Canadian Diabetes Association
Keywords:
body mass index
Canada
obesity
public health
waist circumference
r é s u m é
Mots clés:
indice de masse corporelle
Canada
obésité
santé publique
périmètre abdominal
Le but de cette revue était d’offrir un aperçu du fardeau de l’obésité sur la santé publique au Canada. Selon des
enquêtes représentatives à l’échelle nationale qui ont obtenu des mesures de la stature et du poids, et qui ont
défini l’obésité en utilisant un seuil d’indice de masse corporelle (IMC) de 30 kg/m2, la prévalence de l’obésité
chez les adultes canadiens a augmenté de 10 % en 1970-72 à 26 % en 2009-11. La prévalence de l’obésité chez les
enfants a triplé depuis 1981, et selon les standards de croissance de l’Organisation mondiale de la santé définis
par l’IMC, 12 % des enfants canadiens d’âge scolaire étaient obèses en 2009-11. À ce jour, il y a approximativement 7 millions d’adultes obèses et 600 000 enfants obèses d’âge scolaire au Canada. Les estimations
de la prévalence selon le périmètre abdominal sont d’autant plus troublantes qu’elles indiquent que 37 % des
adultes et 13 % des jeunes ont une obésité abdominale. L’obésité contribue grandement à la morbidité et à la
mortalité dans la population canadienne. Par exemple, de 61 % à 74 % des cas de diabète de type 2, de 17 % à 32 %
des cas d’ostéoarthrite, de 14 % à 21 % des cancers colorectaux, de 8 % à 14 % des cas de dépression et 20 % des
décès prématurés qui surviennent chez les adultes canadiens sont estimés être directement attribuables à
l’obésité. L’obésité constitue également un lourd fardeau économique pour le pays. En 2006, l’obésité comptait
pour 3,9 milliards de dollars en coûts de soins de santé directs (p. ex. les hospitalisations, les médicaments, les
visites chez le médecin et au service des urgences) et 3,2 milliards de dollars en coûts indirects (p. ex. les coûts
liés à l’incapacité et à la perte de productivité en raison de la maladie ou du décès prématuré).
Ó 2013 Canadian Diabetes Association
Introduction
“I couldn’t open up a magazine, you couldn’t read a newspaper,
you couldn’t turn on the TV without hearing about the obesity
epidemic”.
Morgan Spurlock, director and star of Super Size Me.
* Address for correspondence: Ian Janssen, PhD, School of Kinesiology and Health
Studies, Queen’s University, Kingston, Ontario K7L 4V1, Canada.
E-mail address: [email protected].
1499-2671/$ e see front matter Ó 2013 Canadian Diabetes Association
http://dx.doi.org/10.1016/j.jcjd.2013.02.059
As noted by Morgan Spurlock, obesity is a focal point of the
media and is subsequently in the public’s eye. There is a substantial
amount of work being done in Canada to address obesity as
evidence by the fact that there are more than 8000 members
enrolled in the Canadian Obesity Network, Canada’s professional
obesity association for health care providers, researchers, policymakers and obesity stakeholders. Government has also taken an
interest. In fact, the coalition of Federal, Provincial, and Territorial
Ministers of Health and Health Promotion have made childhood
obesity its leading priority (1,2).
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I. Janssen / Can J Diabetes 37 (2013) 90e96
The purpose of this review article is to provide an up-to-date
overview of the public health burden of obesity in Canada. In so
doing, this article will help justify the interest and research that is
being conducted on obesity, and set the stage for other articles
included in this obesity-theme issue. The review is broken down
into 4 sections. The first section provides an overview of how
obesity is defined and measured. The second section discusses the
prevalence of obesity in Canada and how this has changed over
time. The next section covers the health burden of obesity and the
final section provides an overview of the economic burden of
obesity.
Defining and Measuring Obesity
In simple terms, obesity is condition in which excess body fat
has accumulated to the extent that it has an adverse effect on
a person’s physical, mental and/or social health. The Obesity
Society has taken the position that obesity be considered a disease
for the following reasons: 1) considering obesity a disease will
benefit our citizenry by soliciting more resources for prevention
and treatment of, and research on, obesity, 2) considering obesity
a disease will encourage healthcare professionals to view treating
obesity as a vocation worthy of effort and respect, and 3) considering obesity a disease will reduce the stigma and discrimination
experienced by many persons with obesity (3).
The body mass index (BMI), a term originally coined by Ancel
Keys in 1972 (4), is the most widely used method of measuring and
identifying obesity. The BMI cutpoints for adults that are endorsed
by the World Health Organization (WHO) and government and
research agencies in Canada are that overweight (sometimes called
pre-obesity) be based on a BMI of 25e29.9 kg/m2 and obesity a BMI
of 30 kg/m2 (5e7). Obesity can further be divided into class I
(30e34.9 kg/m2), class II (35.0e39.9 kg/m2) and class III (40 kg/m2)
categories (5,6). These BMI cutpoints reflect the increasing health
risk of excess weight as BMI increases above the healthy weight
range of 18.5e24.9 kg/m2. This review primarily focuses on the
obesity range.
The BMI cutpoints used in adults are not appropriate for children. Because BMI changes with normal growth and maturation,
age-specific BMI cut-points are needed for the proper classification
of obesity within the pediatric population (8). Within Canada, 2 sets
of BMI cutpoints are commonly used in children. The first are often
referred to as the Cole or International Obesity Task Force cutpoints
(IOTF), in recognition of the researcher who developed the cutpoints and the organization that initially endorsed their use (9). The
IOTF age- and gender-specific cut-points for 2- to 17-year-olds are
linked, using growth curve trajectories, to the health-based adult
BMI thresholds of 25 kg/m2 (overweight) and 30 kg/m2 (obese) at
entry into adulthood at 18 years of age (9). It is important to note
that these cutpoints are based on a growth reference, which
describes the growth pattern of the population (in this case
representative samples of children from 6 countries), including
both healthy and unhealthy children.
The second set of pediatric BMI cutpoints that are commonly
used in Canada are those of the WHO. In 2005, the WHO released
a set of BMI cutpoints for children aged 0 to 5 years that relied on
growth standards rather than growth references (10). The WHO
growth standards were developed to describe how children should
grow to minimize morbidity risk. The WHO growth standards for 0to 5-year-olds were based on children studied from 6 countries
(Brazil, Ghana, India, Norway, Oman, and the United States). All of
these children lived in conditions favourable to growthdno known
health or environmental constraints to growth, mothers adopted
recommended breast-feeding and nutritional practices, no
maternal smoking during pregnancy, single term birth, and absence
of significant morbidity. Using sophisticated mathematical
91
techniques on historical data sets, the WHO extended their BMI
growth standards from 5 to 19 years of age (11).
In addition to BMI, the waist circumference is also a commonly
used anthropometric measure of obesity, and in particular
abdominal obesity. The amount of visceral fat, located deep in the
abdominal region, is of particular concern to cardiometabolic
diseases (12). Accordingly, measures of abdominal obesity, such the
waist circumference, provide more robust indices of obesityrelated health risk than BMI alone (13). The waist circumference
thresholds that are currently used to denote abdominal obesity in
Canadian men and women are 102 cm and 88 cm, respectively
(6,7). Although the waist circumference is the most popular and
recommended measure, the waist-to-hip ratio and the waist-toheight ratio are other anthropometric measures that are
commonly used to assess abdominal obesity. Issues around these 3
different abdominal obesity measures has been discussed in detail
elsewhere (14).
Although BMI and waist circumference are very useful for
population surveillance and research conducted in groups of
people, these measures are rough guides for predicting obesityrelated risk within a given individual. There are several options
for classifying obesity that rely on these anthropometric measures
and clinical parameters that together guide decision making for
a specific patient. One such system that has recently gained traction
is the Edmonton Obesity Staging System (15). This system is based
on BMI and simple clinical assessments including a medical history,
clinical and functional assessments, and diagnostic investigations
that are widely used in clinical practice and therefore readily
available. Although it is beyond the scope of this article to review
such classification systems in detail, it is important to recognize
that they exist and that they play an important role in the
management of obesity in the medical care setting.
Prevalence of Obesity
BMI
A simple metric that is often used to highlight the magnitude
a public health issue is to determine the prevalence of the condition
and to examine how that prevalence has changed over time. The
prevalence refers to the proportion of the population that has the
condition. Information on the prevalence of obesity in Canadian
adults, based on nationally representative data sets and a BMI
cutpoint of 30 kg/m2, are available from several surveys that date
back as far as 1970. A summary of the findings from these surveys
are provided in Table 1 and illustrated in Figure 1 (16e25). Three
key points can be taken from this table and figure. First, there has
been a steady increase in the prevalence of obesity in Canadian
adults over the past 4 decades, increasing from 10% in the 1970/72
Nutrition Canada Survey (16) to 26% in the 2009/11 Canadian
Health Measures Survey (23). Second, over the last decade the
prevalence of obesity has continued to increase (by about 2% to 3%)
in Canadian adults. This pattern is different than that seen in many
other countries, where the prevalence of obesity leveled off in the
first decade of the 21st century (26). Third, the modality by which
BMI is assessed greatly impacts the prevalence rate such that at any
point in time the prevalence based on measured heights and
weights is much higher than the prevalence based on self-reported
heights and weights, implying that caution should be used when
interpreting data based on self-reported measures. Surveys that
simultaneously collected both measured and self-reported heights
and weights, such as the 2004 Canadian Community Health Survey,
indicate that the typical Canadian adult overestimates their height
and underestimates their weight, and that the prevalence of obesity
is underestimated by about 7% when self-reported measures are
used (25).
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Table 1
Prevalence of obesity in Canadian adults in different national surveys based on a BMI cutpoint of 30 kg/m2
Year of survey
Surveys that obtained measured heights and weights
1970e1972
1978e1979
1981
1986e1992
1988
2004
2005
2008
2007e2009
2009e2011
Surveys that obtained self-reported heights and weights
1985
1990
1994 to 1995
1996 to 1997
1998 to 1999
2000e2001
2003
2005
2007
2007e2009
2008
2009
2010
2011
Survey name and reference
Age limits of
study sample
Prevalence (%) of obesity
Both sexes
Men
Women
Nutrition Canada Survey (16)
Canada Health Survey (17)
Canada Fitness Survey (18)
Canada Heart Health Surveys (19)
Campbell’s Survey on the Well-Being of Canadians (20)
Canadian Community Health Survey (17)
Canadian Community Health Survey (21)
Canadian Community Health Survey (21)
Canadian Health Measures Survey (22)
Canadian Health Measures Survey (23)
18 years
18 years
20 e 69 years
18 e 74 years
20 e 69 years
18 years
18 years
18 years
18 e 79 years
18 e 79 years
9.7
13.8
8.9
14.8
9.1
23.1
24.4
25.1
23.9
26.1
7.6
11.5
8.9
12.4
9.0
22.9
25.7
26.0
24.2
27.2
11.7
15.7
8.9
16.0
9.2
23.2
23.1
24.2
23.6
25.1
Health Promotion Survey (24)
Health Promotion Survey (24)
National Population Health Survey (21)
National Population Health Survey (21)
National Population Health Survey (21)
Canadian Community Health Survey (21)
Canadian Community Health Survey (21)
Canadian Community Health Survey (21)
Canadian Community Health Survey (21)
Canadian Health Measures Survey (25)
Canadian Community Health Survey (21)
Canadian Community Health Survey (21)
Canadian Community Health Survey (21)
Canadian Community Health Survey (21)
18 years
18 years
18 years
18 years
18 years
18 years
18 years
18 years
18 years
18e79 years
18 years
18 years
18 years
18 years
5.6
9.2
12.8
12.3
14.3
14.8
15.3
15.8
16.8
20.2
17.2
17.9
18.1
18.3
NA
NA
12.6
12.9
14.6
15.4
16.0
16.7
17.9
20.7
18.3
19.0
19.8
19.8
NA
NA
13.1
11.7
14.1
14.1
14.5
14.7
15.8
19.7
16.2
16.7
16.5
16.8
BMI, body mass index; NA, not available.
The most current data on obesity in Canadian adults based on
measured heights and weights comes from the 2009/11 Canadian
Health Measures Survey (23). Data from that survey, which are
summarized in Table 2, indicate that 34% of the adult population is
overweight and that an additional 26% are obese. Conversion of
these prevalence values to absolute numbers indicates that there
are approximately 9 million overweight adults and 7 million obese
adults in Canada. It is also noteworthy that 4% of the adult population is in the class III obese category, which equates to almost 1
million people, about two-thirds of whom are women.
Examination of the obesity subclasses in 1978/79 and 2009/11
indicate that the proportion of the obese population that are in the
class II and III categories has increased over time. Specifically, in
1978/79 approximately 17% of obese adults were in the class II
category and 6% were in the class III category (17). In 2009/11
approximately 24% of obese adults were in the class II category and
14% were in the class III category (23). Thus, looking at obesity as
a whole (e.g. BMI 30 kg/m2) does not fully capture the extent to
which obesity-related health risk has changed in the Canadian
population in recent decades.
National level data on the prevalence of obesity in children does
not date back as far as the adult data and is not as abundant
(Table 3) (21,22,27e32). Based on measured heights and weights
and the IOTF cutpoints, the prevalence of childhood obesity
increased from <2% in 1981 (27) to 9% at present (23). Thus, the
prevalence of childhood obesity in Canadian children has tripled in
approximately 1 generation. The most recent survey data for the
pediatric population are based on the 2009/11 Canadian Health
Measures Survey and the WHO cutpoints (Table 4) (23). These data
indicate that 20% of Canadian school-aged children are overweight
and that an additional 12% are obese. Thus, within Canada there are
almost 1 million overweight and 600 000 obese school-aged
children.
Waist circumference and abdominal obesity
Figure 1. Temporal trends in the prevalence (%) of obesity in Canadian adults based on
data from several nationally representative surveys.
The prevalence of abdominal obesity in Canadian adults and
youth is available from 4 surveys that data back to 1981 (Table 5)
(33,34). Within adults, the prevalence of abdominal obesity
increased from 11% in 1981 to 36% in 2007/09 (33). At the same
time, the prevalence of abdominal obesity in youth (12- to 19-yearolds) increased from 2% to 13% (33). It is noteworthy that the
prevalences of overall obesity, as assessed by BMI, and abdominal
obesity, as assessed by waist circumference, were almost identical
in 1981. Conversely, in 2007/09, the prevalence of abdominal
obesity (37% in adults, 13% in youth) was considerably higher than
the prevalence of overall obesity (24% in adults, 8% in youth). This
indicates that over the past 30 years there has been a shift in the
obesity phenotype within Canada. Specifically, for any given BMI
the current population has a higher waist circumference and more
abdominal fat than the population did 30 years ago (35). This is
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93
Table 2
Distribution of the adult (aged 18 years) Canadian population according to BMI category based on measured heights and weights from the 2009e2011 Canadian Health
Measures Survey (23)
BMI range (kg/m2)
BMI category
<18.5
18.5e24.9
25.0e29.9
30
30e34.9
35.0e39.9
40.0
Underweight
Normal weight
Overweight
Obese
Class I
Class II
Class III
Prevalence (%)
Number of people in Canada*
Both sexes
Men
Women
2.0
37.6
34.2
26.1
16.2
6.3
3.6
1.3
31.6
39.9
27.2
19.5
5.5
2.2
2.6
43.7
28.6
25.1
12.9
7.2
5.0
Both sexes
10
9
6
4
1
523
056
057
941
278
694
968
603
449
143
835
833
715
287
Men
4
5
3
2
167
070
139
503
511
708
283
Women
452
360
473
601
773
449
379
5
3
3
1
356
986
917
438
767
986
684
152
089
669
234
061
266
907
BMI, body mass index.
* Estimated by multiplying the prevalence values by the population counts of adults in the 2011 Canadian Census of Population.
another example of why caution should be used when considering
temporal changes in obesity based solely on a BMI threshold of
30 kg/m2. Such an approach can be misleading and lead to an
underestimation of the extent of the changes in obesity and its
impact within the population.
Disparities in obesity
Although the prevalence of obesity is uniformly high, it is not
equal in all demographic groups. There are minimal differences
between males and females, outside of class III obesity which is
about twice as prevalent in women than men (23). The prevalence
of obesity is higher in adults than in children, and within adults the
prevalence goes up across young adult (19% in 18- to 39-year-olds),
middle aged adult (29% in 40- to 59-year-olds), and older adult (34%
in 60- to 79-year-olds) age groups (23). Racial differences also exist.
Data based on self-reported heights and weights from the 2000/03
Canadian Community Health Survey indicate that, unlike our
American neighbours, the prevalence of obesity is comparable in
White (16%), Black (15%), and Latin American (14%) adults (36).
Although the prevalence of obesity was reported to be lower in
East/Southeast Asians (3%) and South Asians (8%) (36) in this
survey, this finding should be interpreted with caution as these
prevalences are based on a BMI cutpoint of 30 kg/m2 and the WHO
recommends that a BMI cutpoint of 27 kg/m2 be used to denote
obesity in these Asian races (37). Conversely, the prevalence of
obesity was considerably higher (27%) in the off-reserve Aboriginals that were studied in the 2000/03 Canadian Community Health
Survey (36). More recent surveys that have collected BMI within
on-reserve Aboriginals indicate that the obesity problem is even
more severe in these communities. For instance, the prevalence of
adult obesity in the 2008/2010 First Nations Regional Health Survey
was 40% (38).
In most industrialized countries there is a clear socioeconomic
status (SES) gradient for obesity such that the highest prevalence of
obesity is observed within the lowest SES groups. The SES gradient,
although present, is not as clear and consistent within Canada for
reasons that are unclear. For instance, data on measured heights
and weights from the 2004 Canadian Community Health Survey
indicated that the prevalence of obesity was higher in women that
did not graduate from high school by comparison to women with
a college or university degree (37% vs. 21%); however, the prevalence of obesity was not different in women in the lowest income
group by comparison to women in the highest income group (21%
vs. 20%) (17). In men, there was a clear SES gradient for obesity
based on both education and income (17).
There are several notable geographic differences in obesity with
Canada. Provincial/Territorial representative data for adults, based on
the last time it was reported for both measured (2004 Canadian
Community Health Survey [17]) and self-reported (2011 Canadian
Table 3
Prevalence of obesity in Canadian children and youth in different national surveys based on BMI
Year of survey
Surveys that obtained measured height and weight
1981
2004
Survey name and reference
Age limit
of sample
Cutpoints used to define obesity
IOTF cutpoints
WHO
cutpoints
7e13 years
2e5 years
6e11 years
12e17 years
12e17 years
12e17 years
6e11 years
12e17 years
3e5 years
5e11 years
12e17 years
1.7 in boys, 2.0 in girls
6.3
8.0
9.4
9.2
7.8
11.6
8.3
3.5
7.9
8.9
NR
10.6
14.3
12.4
NR
NR
13.2
NR
NR
13.1
10.2
Health Behaviour in School-Aged Children Survey (31)
Health Behaviour in School-Aged Children Survey (31)
Canadian Community Health Survey (21)
Health Behaviour in School-Aged Children Survey (31)
11e15
11e15
12e17
11e15
6 in boys, 4 in girls
7 in boys, 4 in girls
4.8
6 in boys, 5 in girls
NR
NR
NR
NR
National Longitudinal Study of Children and Youth (27)
Canadian Health Measures Survey (32)
7e13 years
6e11 years
10.2 in boys, 8.9 in girls
11.7
NR
19.2
Canada Fitness Survey (27)
Canadian Community Health Survey (28)
2005
2008
2007e2009
Canadian Community Health Survey (21)
Canadian Community Health Survey (21)
Canadian Health Measures Survey (22, 29)
2009e2011
Canadian Health Measures Survey (23, 30)
Surveys that obtained self-reported height
and weight from youth
2001e2002
2005e2006
2005
2009e2010
Surveys that obtained parental-reported
height and weight
1996
2007e2009
BMI, body mass index; IOTF, International Obesity Task Force; NR, not reported; WHO, World Health Organization.
years
years
years
years
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Table 4
Distribution of the Canadian school-aged child and youth (aged 5e17 years) population according to BMI category based on the WHO cutpoints and measured
heights and weights from the 2009e2011 Canadian Health Measures Survey (23)
BMI category
Thinness
Normal weight
Overweight
Obese
Number of people in Canada*
Prevalence (%)
Both sexes
Boys
Girls
Both sexes
Boys
2.2
66.4
19.8
11.7
3.2
62.3
19.4
15.1
1.0
70.8
20.2
8.0
106
1 602
993
584
82
1 602
499
388
793
462
573
268
Girls
309
462
001
398
24
1 733
494
195
484
450
572
870
BMI, body mass index; WHO, World Health Organization.
* Estimated by multiplying each prevalence value by the population counts of
5-17 year old children in the 2011 Canadian Census of Population.
Community Health Survey [21]) heights and weights, are provided in
Table 6. Irrespective of time point and measurement modality, the
prevalence of obesity in adults was notably higher than the national
average in the Maritime provinces, Nunavut and Northwest Territories. The prevalence was notably lower than the national average in
Quebec, British Columbia and the Yukon. Gradients in obesity
according to urban/rural location are also evident within Canada,
such that the obesity prevalence is highest in the most rural locations
and lowest within the most urban locations (39). Differences also
exist across urban areas such that adults living in highly sprawled
metropolitan areas with a low population density per land area (e.g.
Halifax, Moncton, Sudbury) have, on average, slightly higher BMI
values than adults living in metropolitan areas that are less sprawled
(e.g. Montreal, Victoria, Windsor) (40). Finally, with a given urban
areas there are neighbourhood differences in BMI and obesity that
could be impacted by social and physical features such as walkability,
presence of parks, and the types of food retailers (41,42).
Health Burden of Obesity
“Thou seest I have more flesh than another man, and therefore
more frailty”
William Shakespeare, The Famous History of the Life of King Henry
the Eight
Relative risks of diseases in obese persons
Hippocrates was the first to note that obesity impacts health
(43). His initial observations were made in 400 BC and were limited
to infertility and early death. At present, there is evidence that
obesity is causally related to dozens of diseases. These diseases
include, but are not limited to: chronic obstructive pulmonary
disease, several cancers (lung, breast cancer, mouth and
oropharynx, esophagus, endometrium, kidney, gallbladder, liver,
prostate), metabolic syndrome, dyslipidemia, non-alcoholic fatty
liver disease, hypertension, congestive heart failure, deep vein
thrombosis, gout, reproductive disorders and infertility (e.g. polycystic ovary syndrome), complications in pregnancy, complications
in surgery, osteoarthritis and back pain.
A common way that researchers quantify the effects of obesity
on individual diseases is to calculate the “relative risk” that a group
of obese participants have of developing a disease relative to
a group of participants with a BMI in the normal weight range.
Relative risk values between 1.01 and 1.49 (or a 1% to 49% increased
risk) reflect a weak effect, relative risk values between 1.5 and 2.99
(or a 50% to 199% increased risk) reflect a moderate effect, whereas
relative risks of 3.0 or greater (or a 200% increased risk) reflect
a strong effect (44). The relative risks that obese persons have of
developing a few of the many diseases that can be caused by
obesity, as obtained from meta-analyses, are shown in Table 7
(45e47). These data show that obesity has subtle effects on some
diseases (e.g. stroke, dementia), modest effects on others (e.g.
colorectal cancer, low back pain) and strong effects on others (e.g.
type 2 diabetes, pulmonary embolism). The full impact of obesity;
however, relates to the fact that obesity impacts such a wide variety
and number of diseases and health conditions.
Population attributable risks for obesity-related diseases
To provide information on the population-level impact of
obesity, information on the prevalence of obesity can be combined
with information of the relative risks of developing a disease to
calculate the population attributable risk (PAR%). The PAR% reflects
the proportion of a disease within the population that is directly
caused or attributable to a specific risk factor, such as obesity. The
PAR% will increase as the prevalence of obesity increases and/or as
the relative risks for the diseases increases. Table 7 contains the
obesity PAR% values for Canadian adults for a few of the many
diseases that can be caused by obesity. For the diseases with small
relative risk values, such as stroke and dementia, the PAR% values
for Canadian adults are in the order of 5% to 10%. For the diseases
with modest relative risk values, such as colorectal cancer and low
back pain, the PAR% values are in the order of 15% to 30%. For the
diseases with strong relative risk values, the PAR% values are above
30%, and in the case of type II diabetes, are in excess of 60%. Thus, it
is clear that within the adult population in Canada a significant
proportion of several chronic diseases are directly attributable to
obesity. Note that a key limitation of the PAR% approach is that the
relative risks that are used for the PAR% calculations are based on
meta-analyses that are not limited to Canadians. Thus, a key
assumption is that the magnitude of the relative risks that occur
globally are consistent in the Canadian population.
Obesity and mortality
The relationship between BMI and mortality risk has been
widely studied and debated. This relationship is often characterized
Table 5
Prevalence of abdominal obesity in Canadian adults and youth in different national surveys based on waist circumference cutpoints of 102 cm in men and 88 cm in women
or equivalent age-specific values in youth
Year of survey
Adults
1981
1986e1992
1988
2007e2009
Youth
1981
1988
2007e2009
Survey name and reference
Age limits of study sample
Prevalence (%) of abdominal obesity
Both sexes
Males
Females
Canada Fitness Survey (33)
Canada Heart Health Surveys (34)
Campbell’s Survey on the Well-Being of Canadians (33)
Canadian Health Measures Survey (33)
20e69
18e74
20e69
20e69
years
years
years
years
11.4
16.5
14.2
35.6
10.1
15.4
12.8
30.7
12.8
17.6
15.5
40.6
Canada Fitness Survey (33)
Campbell’s Survey on the Well-Being of Canadians (33)
Canadian Health Measures Survey (33)
12e19 years
12e19 years
12e19 years
1.8
2.4
12.8
0.6
2.2
9.1
3.0
2.7
16.8
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Table 6
Prevalence of obesity (BMI 30 kg/m2) in Canadian adults by province/territory
Province/territory
2004 Canadian
Community Health
Survey (17) (measured
heights and weights)
2011 Canadian
Community Health
Survey (21)
(self-reported
heights and weights)
Newfoundland and Labrador
Prince Edward Island
Nova Scotia
New Brunswick
Quebec
Ontario
Manitoba
Saskatchewan
Alberta
British Columbia
Nunavut
Northwest Territories
Yukon
33.9
26.3
24.7
29.2
21.8
22.2
28.2
30.8
25.2
19.2
NA
NA
NA
27.3
23.4
23.6
24.9
16.9
18.4
21.8
21.9
19.1
15.1
24.4
27.2
18.7
as being of a U- of J-shape such that mortality risk is increased at
the low and high end of the BMI spectrum relative to the middle of
the spectrum. A recent meta-analysis of 97 studies that collectively
contained 2.88 million people, reported that relative to normal
weight adults, the risk of all-cause mortality was 6% lower in
overweight adults and 18% higher in obese adults (48). Although
mortality risk was not significantly increased in class I obese adults
in that meta-analysis, it was increased by 29% in class II and III
adults (48). Data based on a 13-year follow-up of the 1981 Canada
Fitness Survey, a representative survey of 20- to 64-year-olds,
indicate that the relative risk of mortality is increased by 25% in
class I obese Canadian adults and by 196% in class II and III obese
Canadian adults (18). Based on these relative risk estimates and the
Table 7
Relative risk and PAR% for selected* obesity-related diseases in Canadian adults
Endocrine and metabolic disorders
Type 2 diabetes (45)
Gallbladder disease (45)
Cancer
Colorectal (45)
Pancreatic (45)
Cardiovascular disease
Coronary artery disease (45)
Stroke (45)
Lung disease
Asthma (45)
Pulmonary embolism (45)
Musculoskeletal disorders
Osteoarthritis (45)
Chronic back pain (45)
Mental health disorders
Depression (47)
Dementia (46)
current prevalence of obesity (Table 2) (23) the PAR% value for
premature mortality (e.g. deaths that occur before age 65) in
Canadian adults that is directly attributable to obesity is estimated to
be 20%. Based on this PAR% value and the number of deaths from
all-causes that occurred within 20- to 64-year-old Canadians (52 713
deaths in 2011 [21]), it can be estimated that 10 648 premature
deaths occurred in Canada in 2011 as a direct consequence of
obesity.
Economic Impact of Obesity
BMI, body mass index; NA, not available.
Disease and reference for summary
relative risk
95
Summary
relative risky
Population
attributable
risk (%)z
Men
Women
Men
Women
6.74
1.43
12.41
2.32
60.9
10.4
74.1
24.5
1.95
2.29
1.66
1.60
20.5
25.9
14.2
13.1
1.29
1.23
1.80
1.15
7.3
5.9
16.7
3.6
1.20
3.51
1.25
3.51
5.1
40.5
5.9
38.7
2.76
1.59
1.80
1.59
32.3
13.8
16.7
12.9
1.31
1.42
1.67
1.42
7.7
10.2
14.4
9.5
BMI, body mass index; PAR%, population attributable risk.
* Obesity is a risk factor for several other diseases and medical problems that
include, but may not be limited to: chronic obstructive pulmonary disease, several
cancers (lung, breast cancer, mouth and oropharynx, esophagus, endometrium,
kidney, gallbladder, liver, prostate), metabolic syndrome, dyslipidemia, nonalcoholic fatty liver disease, hypertension, congestive heart failure, deep vein
thrombosis, gout, reproductive disorders/infertility (e.g. polycystic ovary
syndrome), complications in pregnancy, and complications in surgery.
y
Relative risk of developing disease in obese individuals vs. individuals with
a normal BMI as obtained in meta-analyses.
z
Calculated based on the summary relative risks and the prevalence of obesity in
adult men and women in the 2009e2011 Canadian Health Measures Survey.
A common approach for assessing the economic burden of
a condition like obesity is to estimate the impact that it has on
health care expenditures. One method that has been used to
capture the health care costs for obesity in adults in the province of
Ontario is to link population survey data to patient-level administrative data. Such analyses suggest that hospitalization ($67 per
year increase), day procedure ($108 per year increase) and physician costs ($176 per year increase) are all higher in obese adults
than in adults with a normal weight BMI (49). In fact, the total
health care costs was, on average, 25% higher in the obese survey
participants (49). A study of a similar design conducted on grade 5
children (approximately 10 years old) from the province of Nova
Scotia indicated that total direct health care costs over a 3-year
period were 21% higher in obese children than in normal weight
children (50).
Although the aforementioned studies provide insightful information on the health care costs attributable to obesity at the
individual-level, their findings are difficult to extrapolate to the
population-level. The most comprehensive and recent estimates of
the population-level economic burden of obesity in Canadian adults
are for the year 2006 (51). In addition to the direct medical care
costs (e.g. hospitalizations, drug therapy, physician and emergency
room visits, and out-of-pocket costs for medications, supplies and
treatment), the 2006 estimates provide information on indirect
costs (e.g. costs related to short- and long-term disability and lost
productivity due to illness or premature death). These estimates
were generated by multiplying the PAR% for 18 different obesityrelated chronic diseases in Canadian adults by the overall cost of
each of the 18 diseases. The estimates suggest that, in the year 2006,
adult obesity in Canada accounted for $3.9 billion in direct medical
care costs and an addition $3.2 billion in indirect costs. The corresponding costs for overweight (pre-obesity) were $2.1 billion and
$1.9 billion, respectively. Thus, the total economic burden of excess
weight in Canada can be estimated to be in excess of $11 billion
annually. Note that this dollar value has likely increased considerably since 2006 subsequent to population growth, an aging population, and rapidly inflating medical care costs.
“The quality of your life is the quality of your relationships.”
Anthony Robbins, self-help author and motivational speaker
The approaches that have been used to assess the health and
economic burden of obesity in Canada, although informative, are
limited in scope. For instance, although indirect health care costs
capture the costs related to disability and lost productivity that
result from an obesity-related illness, they do not capture losses in
earning power that obese persons may have. As highlighted in
a recent systematic review on the stigma of obesity, obese workers
face stereotypical attitudes from employers and disadvantages in
hiring, promotions and wages because of their weight (52). The
findings from that review also highlight that obese students face
significant obstacles to educational achievement throughout their
schooling years (52), which could ultimately worsen the intellectual capital of the population as a whole. Finally, the social capital of
the population is also negatively impacted by obesity as obese
individuals (particularly females) may be confronted with weight
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bias and negative stereotypes in a range of interpersonal relationships including relationships with sexual partners, parents, siblings
and friends and their overall social network (52).
Conclusion
At present, approximately 8 million Canadians are obese, which
represents 26% of adults and 12% of school-aged children. Even
more troublesome, 37% of adults and 13% of youth are abdominally
obese. Obesity is a major contributor to morbidity and mortality
and it has been estimated that 61% to 74% of type 2 diabetes cases,
17% to 32% of osteoarthritis cases, 14% to 21% of colorectal cancers,
8% to 14% of depression cases, and 20% of premature deaths that
occur in Canadian adults are attributable to obesity. Obesity places
a large economic burden on the country, accounting for $3.9 billion
in direct health care costs and $3.2 billion in indirect costs in 2006.
Acknowledgments
IJ holds a Tier 2 Canada Research Chair award.
Author Disclosures
IJ has received honoraria, speaker fees and consulting fees from
several nonprofit and government organizations that have an
interest in obesity.
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