Many aspects of our environment can contribute to the development of
obesity, including exposure to oversized food portions, lack of physical
activity, which can occur due to high amounts of screen usage and easy
access to unhealthy food.1
Genetic
Some people are genetically predisposed to developing obesity, depending
on their family history.1
Physiological
Broadly speaking, obesity can develop due to an imbalance of energy in
versus energy out, with excess energy being stored as adipose (fat) tissue.1
However, energy balance is a complex mechanism centrally regulated by
the brain through neural and endocrine pathways.2
Through these pathways, hormones and neuropeptides help communicate
with the gut, the pancreas, and visceral adipose tissue to signal energy homeostasis.3
Psychology
Stress, boredom and psychological disorders are linked to overeating and
can contribute to the development of obesity.1,4
Socio-economic
Where a person lives, the society in which they live, and their income
can also influence their chances of developing obesity.5
In lower income countries, people with a high socio-economic status
are more likely to have obesity, whereas in higher income countries,
people with a high socio-economic status are less likely to have obesity.6
Let's start the conversation
Watch the Rethinking Obesity video
Bodyweight classification based on Body Mass Index (BMI).7
BMI=the weight in kilograms divided by the square of the height in
metres (kg/m2).
Classification
BMI (kg/m2)
Normal range
≥18.5 and <25.0
Overweight
≥25.0 and <30.0
Obesity
≥30.0
Obesity, class I
≥30.0 and <35.0
Obesity, class II
≥35.0 and <40.0
Obesity, class III
≥40.0
Waist circumference provides additional information regarding
cardiometabolic risk.7
Waist circumference risk threshold:
Country or ethnic group
Europid, Eastern Mediterranean, Middle Eastern or
Sub-Saharan African
Male
≥94 cm
Female
≥80 cm
South Asian, Chinese or South and Central
American
Male
≥90 cm
Female
≥80 cm
Is obesity a disease?
Obesity Canada:
"Obesity is a chronic and often progressive condition not
unlike diabetes or hypertension."7
TOS (The Obesity Society):
It is the official position of The Obesity Society that obesity
should be declared a disease.8
AACE (American Association of Clinical Endocrinologists):
"[Obesity] must be viewed as a chronic disorder that
essentially requires perpetual care, support, and follow-up."9
CMA (Canadian Medical Association):
"It is important for health care providers to recognize
obesity as a disease so preventive measures can be put in place..."10
WOF (World Obesity Federation):
The World Obesity Federation takes the position that obesity is a
chronic, relapsing, progressive disease process and emphasises the
need for immediate action and the prevention and control of this
global epidemic.11
Acknowledgement of obesity as a disease could improve the overall
management of obesity.12
Obesity is a population problem and should be tackled as such.13
Obesity is one of the most significant contributors to ill health,
replacing traditional public health concerns, such as undernutrition
and infectious disease.13 An integrated approach, requiring
actions from all sectors of society, will be necessary to achieve
effective prevention and management of obesity.13
How have global obesity trends changed?
The global prevalence of obesity has nearly tripled since 1975. In
2016, more than 1.9 billion adults aged ≥18 were overweight. In the
same year, 39% of adults aged ≥18 were living with overweight, and 13%
were living with obesity.14
Female
Male
Obesity is highly prevalent in Canada.
61% of Canadian adults were living with obesity or overweight
in 2016 and 201717
7.21 million Canadian adults self-reported living with
obesity as of 201718
Obesity is associated with multiple comorbidities.19
The weight of obesity on Canadians
Life expectancy decreases with increasing BMI.
Compared to a person with overweight, class I obesity is associated
with a:20
60–120% increased diabetic, renal, and hepatic
mortality
40% increased vascular mortality
20% increased respiratory mortality
Did you know?
The obesity cycle—Reciprocal link between obstructive sleep apnea and obesity.24
Canadians with obstructive sleep apnea are more likely to have
diabetes, hypertension, heart disease and mood disorders.25
What is the link between obesity and cardiovascular disease?
Globally, cardiovascular disease is the leading cause of mortality in
people with obesity.26
The economic weight of obesity in Canada
Conditions associated with obesity have a substantial economic cost.
Obesity was also responsible for high costs associated with its
comorbidities28
Type 2 diabetes: over $1 billion ($746.6 million direct;
$306.0 million indirect costs)
Hypertension: $877 million
($693.2 million direct; $183.5 million indirect costs)
Stroke: $373 million
($305.4 million direct; $67.3 million indirect costs)
Chronic back pain: ($1.59 billion indirect costs)
What are the potential benefits of a weight loss of 5–10%?
How does BMI affect risk of mortality?
Risk of mortality is significantly increased and quality of life is
significantly decreased due to obesity.
Obesity is associated with mental health problems.
People with obesity have a 55% increased risk of developing
depression over time, whereas people with depression have a 58%
increased risk of developing obesity.33
Several studies have found that the effect of weight stigma on
people with obesity may increase vulnerability to depression, low
self-esteem, poor body image, maladaptive eating behaviours and
exercise avoidance.33
Impact of weight loss on cardiovascular risk factors including A1C%, BP, and triglycerides.34
BP, blood pressure; CV, cardiovascular; DBP, diastolic blood
pressure; A1C, glycated haemoglobin; HDL, high density lipoprotein;
SBP, systolic blood pressure.
This data was generated from an observational analysis of 5,145
participants (40.5% male, 37% from ethnic/racial minorities) in the
Look AHEAD (Action for Health in Diabetes) study. The study examined
the association between the magnitude of weight loss and changes in CV
disease risk factors at 1 year. The endpoints measured in this study
include weight (kg), SBP (mmHg), DBP (mmHg), glucose, HcA1c (%), HDL
cholesterol (mg/dL), LDL cholesterol (mg/dL), triglycerides (mg/dL).
* For change in triglycerides, data are median (interquartile
range). The signed-rank test was used to test whether the change from
baseline to year 1 was different from 0.
A weight loss of around 7% has shown a reduction in the incidence of
type 2 diabetes by 58%35†
Every 1 kg of weight loss can decrease LDL levels by 8%36
Achieving 5–10% weight loss can lead to a 30% reduction of sleep
apnea symptoms24‡
† 3234 nondiabetic persons with elevated fasting and post-load
plasma glucose concentrations were randomly assigned to placebo,
metformin (850 mg twice daily), or a lifestyle-modification program
with the goals of at least a 7 percent weight loss and at least 150
minutes of physical activity per week. The mean age of the
participants was 51 years, and the mean body-mass index (the weight in
kilograms divided by the square of the height in meters) was 34.0; 68%
were women, and 45% were members of minority groups. The primary
endpoint in this study was the incidence of diabetes measured with an
annual oral glucose-tolerance test or semi-annual fasting plasma
glucose test.
‡ This data was generated from a population-based prospective
cohort study between July 1989 and January 2000 that included 690
randomly selected employed Wisconsin residents (mean age at baseline,
46 years; 56% male). The participants were evaluated twice at 4-year
intervals for sleep-disordered breathing (SDB). The endpoints for this
study were the percentage change in the apnea-hypopnea index (AHI;
apnea events+hypopnea events per hour of sleep) and odds of developing
moderate-to-severe SDB (defined by an AHI≥15 events per hour of
sleep), with respect to change in weight.
Does obesity affect physical functioning?
The higher the BMI, the greater the risk of impaired physical
functioning, which may include limitations in mobility activities such
as walking and dressing.37
Obesity has a negative impact on physical functioning compared with
normal weight (BMI 18.5–24.9 kg/m2)38
SF-36=Short Form-36 Questionnaire. An established patient survey
used to measure health-related quality of life (HRQoL).
† The SF-36 is comprised of specific domain scores, including
physical functioning.
Adapted from Hopman WM, et al. (2007).
Why is it hard to lose weight and keep it off?
Science has discovered that physiological responses to weight loss
trigger weight regain.
Weight loss in people living with obesity has been shown to cause
changes in appetite hormones that increase hunger and the desire to
eat for at least 1 year.39
Multiple hormones, such as ghrelin, GLP-1, and leptin, play an
important role in regulating appetite.2
Adapted from Sumithran P, et al. (2011); Schwartz A, et al. (2010);
Sumithran P, et al. (2013).
Maintaining weight loss achieved through diet can be challenging.43
A review of 14 long-term studies showed that participants regained
weight after weight loss achieved by dieting.43
Adapted from Mann T, et al. (2007).
Study participants’ weight and diet statuses were assessed at
baseline; their weight was then monitored for up to seven years after
the diet ended. These data are from a review of 14 diet studies with
long-term follow-ups.43
“…the high rate of relapse among people with obesity who have lost
weight has a strong physiological basis and is not simply the result
of the voluntary resumption of old habits."39
Sumithran P, Prendergast LA, Delbridge E, et al. Long-term
persistence of hormonal adaptations to weight loss. N Engl J
Med. 2011;365(17):1597–1604.
Behavioural interventions including diet, exercise, and
cognitive-behavioural therapy are recommended as the first-line
treatment option for people living with overweight or obesity to
achieve clinically important weight loss and reduce obesity-related
symptoms.19 Other treatment options such as
pharmacotherapy and bariatric surgery should not be considered until
behavioural interventions have been unsuccessful.19
The ACTION Study findings
The ACTION (Awareness, Care and Treatment of Obesity MaNagement)
Study is the first Canada-wide study that investigated the
perceptions, attitudes, and perceived barriers to obesity management
among Canadian people living with obesity (PwO), healthcare
professionals (HCPs), and employers. The study was conducted through
an online survey between August and October of 2017. The findings of
this study highlight the misunderstanding and communication gaps that
exist between these groups.44
The majority of the 2545 survey respondents* agreed with the
statement that “obesity is a chronic medical condition”.44
74%of PwO reported that they believe obesity has a large
impact on overall health.
81% of PwO agreed that it would be beneficial to their health
to lose 5–10% of their body weight.
* PwO (n=2000), HCPs (n=395), employers (n=150).
Selected outcomes of the ACTION Study can be grouped into the
following topics:44
1. Weight loss maintenance
The general group of PwO reported engaging in several weight loss attempts.44
The most highly utilized methods for weight loss reported by PwO were:44*
Guidelines suggest that some PwO may face challenges that can prevent
them from maintaining weight loss achieved through diet and exercise.19
* These methods were reported by PwO who made at least one serious
weight loss effort (n=1577) and percentages listed represent the
proportion of respondents who found the method successful based on
their personal criteria.
2. Seeking help
The results of the ACTION Study indicated that most people living
with obesity (74%) considered weight loss to be completely their own responsibility.
The median age at which PwO reported first struggling with excess
weight was 28 years, while they reported first discussing
weight with their HCP at a median age of 39 years.
This indicated a delay of more than 10 years before seeking
medical advice.
Those who reported weight loss
success engaged in these discussions with HCPs earlier than
those who had no current weight-loss success (median: 5 vs. 12
years).
These findings are aligned with the Canadian Obesity Guidelines which
identify that PwO may be reluctant to seek medical attention, which
may pose a barrier to adequate obesity management.19
3. Formal diagnosis
Many PwO (52%) indicated that they had not received a formal
diagnosis of obesity.44
Although 72% of HCPs reported discussing weight with their patients
who are in need of weight management, only 54% of PwO reported
that they have had such discussions in the previous 5 years.
* Among those 54% who reported having a discussion about weight with
their HCP in the past 5 years.
The Canadian Obesity Guidelines recognizes that inadequate education
and the lack of training programs available for physicians act as
barriers to the medical management of obesity.19
4. Patient-provider dialogue
A gap in the patient-provider dialogue was identified, whereby HCPs
reported having discussions about weight management with 72% of their
patients, but only 54% of PwO reported having these discussions in the
past 5 years.44
A delay of more than 10 years was reported from the time that
PwO first started struggling with excess weight to the time they first
discussed weight with their HCP.
Only 28% of PwO who reported having a discussion about weight
with their HCP said that a weight-related follow-up appointment or
call was scheduled.
PwO who reported success in losing weight engaged in discussions with
their HCPs earlier than those who had no current weight loss
success (median: 5 vs. 12 years).
A lack of dialogue about weight management between PwO and HCPs, and
few follow-up appointments may present a challenge to obesity management.
5. Perceptions of wellness offerings
PwO and employers had differing perceptions of the benefit of
employer wellness offerings.44
Employers reported the following weight management benefits offered
by their companies:
The value of wellness programs offered by employers were perceived
differently by employers and PwO.
49% of employers believe that wellness programs contribute
“significantly” or “a lot” to successful weight loss, whereas only
12% of PwO agreed with these statements.
Perceived reasons for non-participation in employer wellness
programs differed between employers and PwO:
35% of employers and 4% of PwO reported that
non-participation is mainly due to lack of interest.
49% of employers and 14% of PwO reported that
non-participation is mainly due to lack of motivation.
50% of employers and 22% of PwO reported that
non-participation is mainly due to PwO feeling uncomfortable.
Skewed perceptions of the value of wellness programs may present a
challenge to effective obesity management.
How can obesity be treated?
Obesity should be treated and managed holistically and as a serious
chronic disease.9,45
Obesity treatment
Behavioural and lifestyle interventions:
For obesity, this should include diet, exercise, and behavioural
modification.43Healthy eating, physical activity, and
cognitive behaviour therapy should be first-line interventions in
all individuals with a BMI ≥25 kg/m2 and they must be
part of any weight loss intervention.19 However,
behavioural interventions may not always be sufficient to maintain
weight loss and some people living with obesity may require a
combination of treatments that includes pharmacotherapy and/or
bariatric surgery to help manage their weight.43
Pharmacotherapy:
For obesity, pharmacotherapy can be considered if lifestyle
interventions do not provide sufficient clinical benefit for
individuals with a BMI of ≥30 kg/m2, or ≥27
kg/m2 with other
comorbidities.19 Pharmacotherapy should be used as an
adjunct to lifestyle modifications and considered if a patient has not
lost 0.5 kg (1 lb) per week by 3–6 months after lifestyle changes.19
Bariatric surgery:
Is the third-line intervention for obesity management, which is
recommended in individuals with a BMI ≥40 kg/m2, or ≥35
kg/m2 with comorbidities.19 Bariatric surgery
can be malabsorptive or restrictive and requires lifelong medical monitoring.19,46
Clinical management of adults who are living with overweight or obesity: Canadian Clinical Practice Guidelines 2006.19
Guidelines for comprehensive medical care of patients with obesity
and overweight according to BMI stage.
Adapted from Lau DCW, et al. (2007).
* Body mass index (BMI) and waist circumference cut-off points are
different for some ethnic groups; refer to Table 3 of Lau DCW, et al.
(2007) for ethnic-specific waist circumference cut-off points.
† Lifestyle modification program consisting of nutrition, physical
activity, and cognitive-behaviour therapy.
‡ Adjunct to lifestyle modification; consider if patient has not
lost 0.5 kg (1 lb) per week by 3–6 months after lifestyle changes.
Pampel FC, et al. Obesity, SES, and
economic development: a test of the reversal hypothesis. Soc Sci
Med. 2012;74(7):1073-1081.
Canadian Obesity Network.
5As of Obesity Management. 2011. Available at: www.obesitynetwork.ca
Retrieved April 1, 2015.
Allison DB, et al. Obesity as a
disease: a white paper on evidence and arguments commissioned by the
Council of the Obesity Society. Obesity (Silver Spring).
2008;16(6):1161-1177.
Mechanick J, et al. American
Association of Clinical Endocrinologists' position statement on
obesity and obesity medicine. Endocr Pract. 2012.
Bray GA, et al. Obesity: a chronic
relapsing progressive disease process. A position statement of the
World Obesity Federation. Obes Rev. 2017;18(7):715-723.
Lobstein T, et al. Comment: obesity as a disease - some
implications for the World Obesity Federation's advocacy and public
health activities. Obes Rev. 2017;18(7):724-726.
World Health Organization. Obesity: preventing and managing the
global epidemic. Report of a WHO consultation. World Health Organ
Tech Rep Ser. 2000;894:1-253.
Lau DC, et al. 2006 Canadian
clinical practice guidelines on the management and prevention of
obesity in adults and children CMAJ. 2007;176(8):1-117.
Prospective Studies Collaboration. Body-mass index and
cause-specific mortality in 900 000 adults: collaborative analyses
of 57 prospective studies. Lancet.
2009;373(9669):1083-1096.
Must A, et al. The disease
burden associated with overweight and obesity. JAMA.
1999;282(16):1523-1529.
Freedhoff Y, et al. Best
weight: a practical guide to office-based obesity
management. Canadian Obesity Network; 2010.
Li C, et
al. Prevalence of self-reported clinically diagnosed sleep apnea
according to obesity status in men and women: National Health and
Nutrition Examination Survey, 2005–2006. Prev Med.
2010;51(1):18-23.
Peppard PE, et al. Longitudinal study
of moderate weight change and sleep-disordered breathing. JAMA.
2000;284(23):3015-3021.
Public Health Agency of Canada.
Fact Facts from the 2009 Canadian Community Health Survey -
Sleep Apnea Rapid Response. Ottawa; 2009.
Afshin A,
et al. Health Effects of Overweight and Obesity in 195 Countries
over 25 Years. N Engl J Med. 2017;377(1):13-27.
Janssen I. The public health burden of obesity in Canada. Can
J Diabetes 2013;37(2):90-96.
Anis AH, et al. Obesity
and overweight in Canada: an updated cost‐of‐illness study. Obes
Rev. 2010;11(1):31-40.
Diabetes Prevention Program
Research Group. Reduction in the incidence of type 2 diabetes with
lifestyle intervention or metformin. N Engl J Med.
2002;2002(346):393-403.
Brown JD, et al. Effects on
cardiovascular risk factors of weight losses limited to 5-10.
Translational behavioral medicine. 2016;6(3):339-346.
Warkentin L, et al. The effect of weight loss on health‐related
quality of life: systematic review and meta‐analysis of randomized
trials. Obes Rev. 2014;15(3):169-182.
Grover SA, et
al. Years of life lost and healthy life-years lost from diabetes and
cardiovascular disease in overweight and obese people: a modelling
study. Lancet Diabetes Endocrinol 2015;3(2):114-122.
National Obesity Observatory. Obesity and mental health.
2011.
Wing RR, et al. Benefits of modest weight loss in
improving cardiovascular risk factors in overweight and obese
individuals with type 2 diabetes. Diabetes Care.
2011;34(7):1481-1486.
Diabetes Prevention Program
Research Group. Reduction in the Incidence of Type 2 Diabetes with
Lifestyle Intervention or Metformin. New England Journal of
Medicine. 2002;346(6):393-403.
Kapur NK, et al. High
density lipoprotein cholesterol: an evolving target of therapy in
the management of cardiovascular disease. Vasc Health Risk Manag.
2008;4(1):39-57.
Syddall HE, et al. The SF-36: a simple,
effective measure of mobility-disability for epidemiological
studies. JNHA-The Journal of Nutrition, Health and Aging.
2009;13(1):57-62.
Hopman WM, et al. The association
between body mass index and health-related quality of life: data
from CaMos, a stratified population study. Quality of life
research. 2007;16(10):1595-1603.
Sumithran P, et al.
Long-term persistence of hormonal adaptations to weight loss. New
England Journal of Medicine. 2011;365(17):1597-1604.
Schwartz A, et al. Relative changes in resting energy
expenditure during weight loss: a systematic review. Obesity
Reviews. 2010;11(7):531-547.
Sumithran P, et al. The
defence of body weight: a physiological basis for weight regain
after weight loss. Clinical Science.
2013;124(4):231-241.
Rosenbaum M, et al. Energy intake in
weight-reduced humans. Brain Research. 2010;1350:95-102.
Mann T, et al. Medicare's search for effective obesity
treatments: diets are not the answer. American Psychologist.
2007;62(3):220.
Sharma AM, et al. Perceptions of barriers
to effective obesity management in Canada: Results from the ACTION
study. Clin Obes. 2019;9(5):e12329.
Garvey WT, et
al. American Association of Clinical Endocrinology Comprehensive
Clinical Practice Guidelines for Medical Care of Patients with
Obesity. Endocr Pract. 2016;22 Suppl 3:1-203.
Obesity Action Coallation. What is Obesity Treatment? Bariatric
Surgery. Available at: https://www.obesityaction.org/obesity-treatments/what-is-obesity-treatment/bariatric-surgery/.
Retrieved May 22, 2019.