Obesity is a prevalent, complex, progressive and relapsing chronic disease, characterized by abnormal or excessive body fat (adiposity), that impairs health.
People living with obesity face substantial bias and stigma, which contribute to increased morbidity and mortality independent of weight or body mass index.
This guideline update reflects substantial advances in the epidemiology, determinants, pathophysiology, assessment, prevention and treatment of obesity, and shifts the focus of obesity management toward improving patient-centred health outcomes, rather than weight loss alone.
Obesity care should be based on evidence-based principles of chronic disease management, must validate patients’ lived experiences, move beyond simplistic approaches of “eat less, move more,” and address the root drivers of obesity.
People living with obesity should have access to evidence-informed interventions, including medical nutrition therapy, physical activity, psychological interventions, pharmacotherapy and surgery.
Obesity is a complex chronic disease in which abnormal or excess body fat (adiposity) impairs health, increases the risk of long-term medical complications and reduces lifespan.1 Epidemiologic studies define obesity using the body mass index (BMI; weight/height2), which can stratify obesity-related health risks at the population level. Obesity is operationally defined as a BMI exceeding 30 kg/m2 and is subclassified into class 1 (30–34.9), class 2 (35–39.9) and class 3 (≥ 40). At the population level, health complications from excess body fat increase as BMI increases.2 At the individual level, complications occur because of excess adiposity, location and distribution of adiposity and many other factors, including environmental, genetic, biologic and socioeconomic factors (Box 1).11
Complications of obesity
Adipose tissue not only influences the central regulation of energy homeostasis, but excessive adiposity can also become dysfunctional and predispose the individual to the development of many medical complications, such as:
Excess and ectopic body fat are important sources of adipocytokines and inflammatory mediators that can alter glucose and fat metabolism, leading to increased cardiometabolic and cancer risks, and thereby reducing disease-free duration and life expectancy by 6 to 14 years.1,7,8 It is estimated that 20% of all cancers can be attributed to obesity, independent of diet.9 Obesity increases the risk of the following cancers:10
Colon (both sexes)
Kidney (both sexes)
Esophagus (both sexes)
Endometrium (women)
Postmenopausal breast (women)
Over the past 3 decades, the prevalence of obesity has steadily increased throughout the world,12 and in Canada, it has increased threefold since 1985.13 Importantly, severe obesity has increased more than fourfold and, in 2016, affected an estimated 1.9 million Canadian adults.13
Obesity has become a major public health issue that increases health care costs14,15 and negatively affects physical and psychological health.16 People with obesity experience pervasive weight bias and stigma, which contributes (independent of weight or BMI) to increased morbidity and mortality.17
Obesity is caused by the complex interplay of multiple genetic, metabolic, behavioural and environmental factors, with the latter thought to be the proximate cause of the substantial rise in the prevalence of obesity.18,19 A better understanding of the biological underpinnings of this disease has emerged in recent years.19 The brain plays a central role in energy homeostasis by regulating food intake and energy expenditure (Box 2).24
Appetite regulation20–23
The control of appetite is complex and involves the integration of the central neural circuits including the hypothalamus (homeostatic control), the mesolimbic system (hedonic control) and the frontal lobe (executive control).
The crosstalk between homeostatic and hedonic eating is influenced by mediators from adipose tissue, the pancreas, gut and other organs.
Cognitive functions in the prefrontal cortex exert executive control on food choices and the decision to eat. The interconnectivity of these neural networks drives eating behaviour and has been shown to be altered in obesity.
Decreased food intake and increased physical activity lead to a negative energy balance and trigger a cascade of metabolic and neurohormonal adaptive mechanisms.25,26 Therapies that target these alterations in neurohormonal mechanisms can become effective tools in the long-term management of obesity.27
Novel approaches to diagnose and assess obesity in clinical practice have been proposed.11,18,19,28 Although BMI is widely used to assess and classify obesity (adiposity), it is not an accurate tool for identifying adiposity-related complications.19 Waist circumference has been independently associated with an increase in cardiovascular risk, but it is not a good predictor of visceral adipose tissue on an individual basis.29 Integration of both BMI and waist circumference in clinical assessment may identify the higher-risk phenotype of obesity better than either BMI or waist circumference alone, particularly in those individuals with lower BMI.30,31 In addition to BMI and waist circumference measurements, a comprehensive history to identify the root causes of obesity, appropriate physical examination and relevant laboratory investigations will help to identify those who will benefit from treatment.32
The Edmonton obesity staging system has been proposed to guide clinical decisions from the obesity assessment and at each BMI category (Appendix 1, available at www.cmaj.ca/lookup/suppl/doi:10.1503/cmaj.191707/-/DC2).28 This 5-stage system of obesity classification considers metabolic, physical and psychological parameters to determine the optimal obesity treatment. In population studies, it has been shown to be a better predictor of all-cause mortality when compared with BMI or waist circumference measurements alone.33,34
There is a recognition that obesity management should be about improved health and well-being, and not just weight loss.34–36 Because the existing literature is based mainly on weight-loss outcomes, several recommendations in this guideline are weight-loss centred. However, more research is needed to shift the focus of obesity management toward improving patient-centred health outcomes, rather than weight loss alone.
Despite growing evidence that obesity is a serious chronic disease, it is not effectively managed within our current health system.37,38 Canadian health professionals feel ill equipped to support people living with obesity.39–41 Biased beliefs about obesity also affect the level and quality of health care that patients with obesity receive.42 The dominant cultural narrative regarding obesity fuels assumptions about personal irresponsibility and lack of willpower and casts blame and shame upon people living with obesity.41 Importantly, obesity stigma negatively influences the level and quality of care for people living with obesity.42
With increased knowledge of the disease state and better approaches to assess and manage obesity, it is timely to update the 2006 Canadian clinical practice guideline.43 The goal of this update is to disseminate to primary care practitioners evidence-informed options for assessing and treating people living with obesity. Importantly, this guideline incorporates the perspectives of people with lived experience and of interprofessional primary care providers with those of experts on obesity management, and researchers. This article is a summary of the full guideline, which is available online (http://obesitycanada.ca/guidelines/).
Scope
The target users for this guideline are primary health care professionals. The guideline may also be used by policy-makers and people affected by obesity and their families. The guideline is focused on obesity in adults. The recommendations are intended to serve as a guide for health care providers; clinical discretion should be used by all who adopt these recommendations. Resource limitations and individual patient preferences may make it difficult to put every recommendation into practice, but the guideline is intended to improve the standard of, and access to, care for individuals with obesity in all regions of Canada.
Recommendations
This clinical practice guideline informs the arc of the patient journey and clinical management approach in the primary care setting. The guideline recommendations are shown in Table 1.
Recommendations on management of obesity in adults*
A complete description of the recommendations and supporting evidence are available in the 19 chapters of the full guideline (http://obesitycanada.ca/guidelines/). This synopsis outlines a discussion of the guiding principles that the executive committee determined as important for advancing clinical practice in Canada.
There are 5 steps in the patient arc to guide a health care provider in the care of people living with obesity. Each step is outlined below with highlights of the relevant recommendations and a discussion of supporting evidence.
Recognition of obesity as a chronic disease by health care providers, who should ask the patient permission to offer advice and help treat this disease in an unbiased manner.
Assessment of an individual living with obesity, using appropriate measurements, and identifying the root causes, complications and barriers to obesity treatment.
Discussion of the core treatment options (medical nutrition therapy and physical activity) and adjunctive therapies that may be required, including psychological, pharmacologic and surgical interventions.
Agreement with the person living with obesity regarding goals of therapy, focusing mainly on the value that the person derives from health-based interventions.
Engagement by health care providers with the person with obesity in continued follow-up and reassessments, and encouragement of advocacy to improve care for this chronic disease.
Step 1: Recognition of obesity as a chronic disease and obtaining patient permission
Primary care providers should recognize and treat obesity as a chronic disease, caused by abnormal or excess body fat accumulation (adiposity), which impairs health, with increased risk of premature morbidity and mortality.1,2,18,44–47
Obesity is a complex and heterogeneous chronic disease that does not present in the same way in all patients and that requires individualized treatment and long-term support like any other complex chronic disease.
Weight bias in health care settings can reduce the quality of care for patients living with obesity.42 A key to reducing weight bias, stigma and discrimination in health care settings is for health care providers to be aware of their own attitudes and behaviours toward individuals living with obesity.48 This can be achieved by completing a self-assessment tool, like the Implicit Association Test, for weight bias.49 A full description and supporting evidence for weight bias recommendations are available online (http://obesitycanada.ca/guidelines/) in the chapter titled “Reducing weight bias in obesity management, practice and policy.”
Health care providers should not assume that all patients living with obesity are prepared to initiate obesity management. Health care providers should ask the patient permission to discuss obesity, and if the patient permits, then a discussion on treatment can begin.50,51
Step 2: Assessment
Primary care clinicians should promote a holistic approach to health with a focus on health behaviours in all patients and address the root causes of weight gain with care to avoid stigmatizing and overly simplistic narratives.
Direct measurement of height, weight and waist circumference and calculation of BMI should be included in routine physical examination for all adults. Although BMI has its limitations, it remains a valuable tool for screening purposes and for population health indices.52 For persons with increased BMI (between 25 mg/m2 and 34.9 mg/m2), waist circumference should be regularly measured to identify individuals with increased visceral adiposity and adiposity-related health risks.53
Root causes of obesity include biological factors such as genetics, epigenetics, neurohormonal mechanisms, associated chronic diseases and obesogenic medications, sociocultural practices and beliefs, social determinants of health, built environment, individual life experiences like adverse childhood experiences, and psychological factors such as mood, anxiety, binge-eating disorder, attention-deficit/hyperactivity disorder, self-worth and identity.50 Working with people to understand their context and culture, and integrate their root causes, allows for the development of personalized plans. These plans can be integrated into long-term therapeutic relationships with chronic disease follow-up of obesity and related comorbidities, including addressing the root causes of obesity such as existing conditions and obesogenic medications.
We recommend obtaining a comprehensive history to identify these root causes of weight gain, as well as physical, mental and psychosocial barriers. Physical examination, laboratory, diagnostic imaging and other investigations should be carried out based on clinical judgment. We also recommend measuring blood pressure in both arms and obtaining fasting glucose or glycated hemoglobin values and a lipid panel to determine cardiometabolic risk, and when indicated, alanine aminotransferase to screen for nonalcoholic fatty liver disease.
Step 3: Discussion of treatment options
Adults living with obesity should receive individualized care plans that address their root causes of obesity and that provide support for behavioural change (e.g., nutrition, physical activity) and adjunctive therapies, which may include psychological, pharmacologic and surgical interventions.
Nutrition and exercise
All individuals, regardless of body size or composition, would benefit from adopting a healthy, well-balanced eating pattern and engaging in regular physical activity. Aerobic activity (30–60 min) on most days of the week can lead to a small amount of weight and fat loss, improvement in cardiometabolic parameters, and weight maintenance after weight loss.54
Weight loss and weight-loss maintenance require a long-term reduction in caloric intake. Long-term adherence to a healthy eating pattern that is personalized to meet individual values and preferences, while fulfilling nutritional needs and treatment goals, is an important element of managing health and weight.
Medical nutrition therapy is a foundation for chronic disease management, including obesity management.55,56 However, medical nutrition therapy should not be used in isolation in obesity management, as sustaining weight loss may be difficult long term because of compensatory mechanisms in the brain that promote positive caloric intake by increasing hunger and ultimately causing weight gain.57,58 Instead, medical nutrition therapy, in combination with other interventions (psychological, pharmacologic, surgical), should be tailored to meet an individual’s health-related or weight-related outcomes.56,59
The weight loss achieved with health behavioural changes is usually 3%–5% of body weight, which can result in meaningful improvement in obesity-related comorbidities.60 The amount of weight loss varies substantially among individuals, depending on biological and psychosocial factors and not simply on individual effort.
The weight at which the body stabilizes when engaging in healthy behaviours can be referred to as the “best weight”; this may not be an “ideal” weight on the BMI scale. Achieving an “ideal” BMI may be very difficult. If further weight loss is needed to improve health and well-being beyond what can be achieved with behavioural modification, then more intensive pharmacologic and surgical therapeutic options can be considered.
Psychological and behavioural interventions
All health interventions such as healthy eating and physical activity strategies, medication adherence or surgery preparation and adjustment approaches rest on behaviour change.61 Psychological and behavioural interventions are the “how to” of change. They empower the clinician to guide the patient toward recommended behaviours that can be sustained over time.60 A full description of psychological and behavioural interventions and supporting evidence are available online (http://obesitycanada.ca/guidelines/) in the chapter titled “Effective psychological and behavioural interventions in obesity management.”
Pharmacotherapy
We recommend adjunctive pharmacotherapy for weight loss and weight-loss maintenance for individuals with BMI ≥ 30 kg/m2 or BMI ≥ 27 kg/m2 with adiposity-related complications, to support medical nutrition therapy, physical activity and psychological interventions. Options include liraglutide 3.0 mg, naltrexone-bupropion combination and orlistat. Pharmacotherapy augments the magnitude of weight loss beyond that which health behaviour changes can achieve alone and is important in the prevention of weight regain.62–66 A full description and supporting evidence are available online (http://obesitycanada.ca/guidelines/) in the chapter titled “Pharmacotherapy in obesity management.”
Bariatric surgery
Bariatric surgery may be considered for people with BMI ≥ 40 kg/m2 or BMI ≥ 35 kg/m2 with at least 1 obesity-related disease. The decision regarding the type of surgery should be made in collaboration with a multidisciplinary team, balancing the patient’s expectations, medical condition, and expected benefits and risks of the surgery. A full description and supporting evidence are available online (http://obesitycanada.ca/guidelines/) in the chapters titled “Bariatric surgery: selection and preoperative workup,” “Bariatric surgery: options and outcomes” and “Bariatric surgery: postoperative management.”
Step 4: Agreement regarding goals of therapy
Because obesity is a chronic disease, managing it in the long term involves patient–provider collaboration.67 Health care providers should talk with their patients and agree on realistic expectations, person-centred treatments and sustainable goals for behaviour change and health outcomes.68
Helpful actions in primary care consultations to mitigate antifat stigma include explicitly acknowledging the multiple determinants of weight-disrupting stereotypes of personal failure or success attached to body composition; focusing on behavioural interventions to improve overall health; and redefining success as healthy behaviour change regardless of body size or weight.69
As this disease is chronic in nature, the treatment plan must be long term. Health care providers and patients should design and agree on a personalized action plan that is practical and sustainable and addresses the drivers of weight gain.70
Step 5: Follow-up and advocacy
There is a need to advocate for more effective care for people living with obesity. This includes improving the education and lifelong learning of health care providers to be able to deliver effective, evidence-based obesity care. We also need to support allocation of health care resources to improve access to effective behavioural, pharmacologic and surgical therapeutic options.
There are substantial barriers affecting access to obesity care in Canada, including a profound lack of interdisciplinary obesity management programs, a lack of adequate access to health care providers with expertise in obesity, long wait times for referrals and surgery, and the high costs of some treatments.,37,71–73 In general, health care professionals are poorly prepared to treat obesity. 74 None of the anti-obesity medications available in Canada is listed as a benefit on any provincial or territorial formulary and none is covered under any provincial public drug benefit or pharmacare program.71 Wait times for bariatric surgery in Canada are the longest of any surgically treatable condition.37,71 Although access to bariatric surgery has increased in some parts of Canada, it is still limited in most provinces and nonexistent in the 3 territories. 37,71,75 Patients referred to bariatric surgery can wait as long as 8 years before meeting a specialist or receiving the surgery.
The lack of access to obesity treatments is contributing to rising levels of severe obesity in Canada.46 Canadians affected by obesity are left to navigate a complex landscape of weight-loss products and services, many of which lack a scientific rationale and openly promote unrealistic and unsustainable weight-loss goals.76
Methods
Composition of participating groups
Obesity Canada and the Canadian Association of Bariatric Physicians and Surgeons assembled an executive committee and steering committee with broad expertise and geographic representation. The executive committee (comprising 2 co-chairs [S.W., D.C.W.L.], a primary care physician [D.C.-S.], a psychologist [M.V.], a bariatric surgeon [L.B.] and a nephrologist [A.M.S.]) provided overall vision and oversight for the guideline process.
The steering committee (n = 16) consisted of some lead authors of each chapter and a person living with obesity; this committee identified additional researchers (chapter leads and authors) to write each chapter. The executive committee and steering committee met in person in April 2017 and December 2017 and at least monthly by phone.
Chapter leads and chapter authors (n = 60) were selected based on their expertise in clinical practice and research in the field of obesity medicine. The number of chapter authors per chapter ranged from 2 to 4. Some chapter leads identified additional authors to participate in writing each chapter.
We engaged people living with obesity (n = 7) through participation of the Public Engagement Committee of Obesity Canada. One member of the Public Engagement Committee (I.P.) was assigned to the steering committee for this guideline. The Public Engagement Committee met by phone once per month. We obtained contributions from committee members through online surveys, focus groups and individual conversations.
We engaged Indigenous community members through a focus group (n = 14). Additionally, we obtained the insights of health care providers working with Indigenous communities via a consensus-building process between these clinicians and chapter authors, carried out over the spring of 2019, which further grounded evidence in clinical practice. Details are available online (http://obesitycanada.ca/guidelines/) in the chapter titled “Obesity management with Indigenous Peoples.”
Obesity Canada staff, consultants and volunteers (n = 15) provided administrative support and project coordination for the guideline development process. Table 2 outlines the guideline development process and the responsibilities of each group of participants.
Summary of guideline development process
Selection of priority topics
The executive committee conducted a mind-mapping exercise to identify the scope of the guideline and the broad sections and chapters (April–June 2017).79 A total of 19 different sections and chapters were prioritized. The steering committee developed PI/PECOT (Population, Intervention or Exposure, Comparison, Outcome, Time) questions for each chapter at an in-person meeting on Dec. 15–16, 2017, resulting in 179 questions to guide the literature search. All clinical questions were developed with the assistance of the McMaster Evidence Review and Synthesis Team (MERST; previously the McMaster Evidence-Based Practice Centre) in the appropriate format (e.g., PICO [T] for therapeutics and treatments, PEO for qualitative questions).
Literature review and quality assessment
The McMaster Evidence Review and Synthesis Team supported the guideline development through literature searches based on the PI/PECOT questions for each chapter. A health sciences librarian, based at McMaster Health Sciences Library (Hamilton, Ont.), used this information to create search strategies for the MEDLINE and Embase databases. The searches were for peer-reviewed and published literature in the English language; the search dates were January 2006 to June 2018. There were 14 searches that mapped directly to the chapters and another 7 searches that helped provide context for various chapters. Search strategies are available on the obesity guideline webpage (http://obesitycanada.ca/guidelines/). Once a search was conducted, the results were uploaded to EndNote, where the duplicates were removed and the final set of citations was uploaded to DistillerSR software for selection and review.80 In addition to the electronic searches, the chapter authors identified additional citations and added them to the main search results.
Two reviewers completed screening of article titles and abstracts and independently selected studies for possible inclusion. Any citation that was selected for inclusion by either reviewer was moved to full-text review. One or more authors of the relevant chapter conducted reviews of full-text articles for relevancy. Selected citations were then assessed for their methodological quality using the Shekelle approach.77,81 Each citation was categorized into prevention, treatment, evaluation of diagnostic properties or prognosis. Once that selection was made, the appropriate methods worksheet was displayed in the DistillerSR platform, from which the methodological questions were answered and a level of evidence generated based on the type and quality of the study. The levels of evidence informed the strength of the recommendations and were generated from the methods worksheets (Box 3).77
Classification schemes77
Category of evidence
Level 1a: Evidence from meta-analysis of randomized controlled trials (RCTs)
Level 1b: Evidence from at least 1 RCT
Level 2a: Evidence from at least 1 controlled study without randomization
Level 3: Evidence from nonexperimental descriptive studies, such as comparative studies, correlation studies and case–control studies
Level 4: Evidence from expert committee reports or opinions or clinical experience of respected authorities, or both
Strength of recommendation
Grade A: Directly based on level 1 evidence
Grade B: Directly based on level 2 evidence or extrapolated recommendation from category 1 evidence
Grade C: Directly based on level 3 evidence or extrapolated recommendation from level 1 or 2 evidence
Grade D: Directly based on level 4 evidence or extrapolated recommendation from level 1, 2 or 3 evidence
Adapted with permission from BMJ Publishing Group Limited. Shekelle PG, Woolf SH, Eccles M, et al. Developing clinical guidelines. West J Med 1999;170:348-51.
Development of recommendations
Recommendations were formulated by the steering committee, chapter leads and chapter authors based on the highest level of evidence available (Box 3).77 Chapter leads and authors reviewed the type and strength of the available evidence (level) and added the study reference that provided the highest level of evidence for the specific recommendation.
Recognizing the importance of qualitative research in addressing questions pertinent to the care of people living with obesity, content experts in qualitative research (S.K., X.R.S., D.C.S., L.C., S.R.M.) were involved in the review of all materials informing these recommendations. Consensus appraisal of evidence quality by reviewers with expertise in qualitative methods informed the level of evidence in these recommendations.
Some grade D recommendations were formulated based on expert committee reports, opinions or clinical experience of respected authorities, and referenced accordingly; other grade D recommendations formulated by chapter authors were noted with “Consensus” after the grade D.
Chapter authors used a standardized terminology to make the recommendation more specific. The actionable verbs used for each of the recommendations were informed by the literature (Table 3).82–84
We used an iterative process to finalize the recommendations. Methodologists from MERST provided an independent review of recommendations that had a grade between A and C, for which they examined the clarity of wording and the fidelity of the recommendations with the evidence. Two methodologists (a primary and secondary reviewer) reviewed each recommendation, using checklists as a guide for assigning levels of evidence to each citation. The methodologists met, discussed and reached consensus on grading the recommendations, and reported their suggestions regarding revisions to the wording or grading to the executive committee. Chapter leads edited the recommendations based on the MERST review process.
The executive committee voted on each recommendation, to ensure consensus. If a recommendation did not reach 100% agreement, the executive committee discussed the recommendation in depth until consensus was achieved. The chapter leads subsequently modified the wording of this recommendation, as required, and the executive committee approved the newly worded recommendation. The executive committee provided final approval of all the recommendations. All the recommendations included in this guideline achieved 100% agreement.
External review
External reviewers (primary care health care professionals and people living with obesity [n = 7]) reviewed the recommendations for relevance and feasibility. We made some modifications to reflect language and the context of the primary care setting. A separate external peer review was conducted for each chapter.
Management of competing interests
Funding came from the Canadian Institutes of Health Research Strategic Patient-Oriented Research initiative, Obesity Canada’s Fund for Obesity Collaboration and Unified Strategies (FOCUS) initiative, the Canadian Association of Bariatric Physicians and Surgeons, and in-kind support from the scientific and professional volunteers engaged in the process. The views of the funding body have not influenced the content of the guideline. All committee members (executive and steering committees), chapter leads and chapter authors were volunteers and not remunerated for their services.
The executive committee developed and managed the competing interest policy and procedures for mitigating bias. The policy and disclosures of competing interest are available on the guideline website. All participants were required to disclose potential competing interests. We maintained detailed competing interest declarations throughout the process for all members of the steering and executive committees, as well as the participating methodologists from MERST. We used the International Committee of Medical Journal Editors’ disclosure form, with the addition of government funding sources.
Individuals with relevant disclosures were not excluded from conducting the critical appraisals or voting on recommendations. However, the executive committee asked individuals with direct competing interests to abstain from voting in the areas in which they had the conflict. Any discussion regarding off-label use of drugs included the caveat that the use was off label.
As mentioned earlier, methodologists from MERST who had no competing interests reviewed and graded78 each included study to ensure the evidence had been appropriately assessed. They also reviewed the recommendations (graded between A and C) to ensure that recommendations were aligned with the evidence. Finally, we conducted an external review process to assess the feasibility of the recommendations and evaluate for the presence of bias.
Implementation
Obesity Canada and the Canadian Association of Bariatric Surgeons and Physicians have created a joint guideline website (http://obesitycanada.ca/guidelines) that hosts the full guideline; interim updates; a quick reference guide; key messages; health care provider tools, slide kits, videos and webinars; and resources for people living with obesity and their support systems, in English and French. The guideline will be hosted on the website as a living document. Each chapter lead will monitor evidence related to this guideline and will collaborate with the executive committee to update the recommendations if new evidence becomes available that could influence the recommendations. A framework for implementation (5As Framework) is available in Appendix 2.
More than 10 years after the release of the first Canadian obesity guideline in 2006, access to obesity care remains an issue in Canada.37,71 Obesity is not officially recognized as a chronic disease by the federal, provincial and territorial, and municipal governments, despite declarations by the Canadian Medical Association85 and the World Health Organization.86 The lack of recognition of obesity as a chronic disease by public and private payers, health systems, the public and media has a trickle-down effect on access to treatment.72 Obesity continues to be treated as a self-inflicted condition, which affects the type of interventions and approaches that are implemented by governments or covered by health benefit plans.87
Implementation of this guideline will require targeted policy action, as well as advocacy efforts and engagement from people living with obesity, their families and health care providers. Canadian organizations have come together to change the narrative regarding obesity in Canada, to eliminate weight bias and obesity stigma, and to change the way health care systems and policies approach obesity.88 This guideline will be used to assist in advocacy efforts to federal and provincial governments to improve the care of individuals with obesity.
Other guidelines
In 2006, the first evidence-based Canadian clinical practice guideline on the prevention and management of obesity in adults and children was released.43 In 2015, the Canadian Task Force on Preventive Health Care, in collaboration with scientific staff of the Public Health Agency of Canada and the McMaster Evidence Review and Synthesis Centre, released a set of recommendations for prevention of weight gain and use of behavioural and pharmacologic interventions to manage overweight and obesity in adults in primary care.89 This guideline was not designed to “apply to people with BMI of 40 or greater, who may benefit from specialized bariatric programs” and reviewed only intervention trials conducted in settings generalizable to Canadian primary care. The guideline also did not include surgical treatments.
Gaps in knowledge
The recommendations in this guideline are informed by the best level of evidence available in 2020. We acknowledge that ongoing research will continue to inform and advance obesity management.90,91
Current treatment options, apart from surgical intervention, rarely yield sustained weight loss beyond 20%, and for some people living with obesity, this level of weight loss may be inadequate for the resolution or improvement of many adiposity-related medical complications. There is a need for more treatment options to meet the needs of people with obesity. Weight regain continues to be a challenge for many patients who have received treatment.92
Conclusion
Obesity is a prevalent, complex chronic disease that affects a large number of adults in Canada and globally, and yet only a small fraction of people living with obesity who could benefit from treatment have access to care. This updated evidence-informed guideline is an attempt to enhance access and care by people living with obesity through recognition among health care providers that obesity requires long-term treatment. The newer insights into appetite regulation and the pathophysiology of obesity have opened new avenues for treating this chronic disease. Reducing weight bias and stigma, understanding the root causes of obesity, and promoting and supporting patient-centred behavioural interventions and appropriate treatment by health care providers — preferably with the support of interdisciplinary care teams — will raise the standards of care and improve the well-being of people living with obesity. Dissemination and implementation of this guideline are integral components of our goals to address this prevalent chronic disease. Much more effort is needed to close the gaps in knowledge through obesity research, education, prevention and treatment.
Acknowledgements
The authors thank Obesity Canada staff members Dawn Hatanaka, Nicole Pearce, Brad Hussey, Robert Fullerton and Patti Whitefoot-Bobier for their coordinating support as well as their contributions for the development of the Obesity Guidelines website, online resources, tables and figures. The authors also thank members of the Obesity Canada Public Engagement Committee (Lisa Schaffer, Candace Vilhan, Kelly Moen, Doug Earle, Brenndon Goodman), who contributed to the creation of the research questions and reviewed key messages for individuals living with obesity and recommendations for health care providers. The authors also thank McMaster Evidence Review and Synthesis Team (MERST) member Donna Fitzpatrick, who played a critical role in developing the methods needed for the guideline; and thank the reviewers whose comments helped to improve the chapters and this manuscript. The authors thank Barbara Kermode-Scott and Brad Hussey for editing the guidelines, Elham Kamran and Rubin Pooni for research assistance, and Jordan Tate from the Physician Learning Program at the University of Alberta for designing the 5As framework for the guideline.
Footnotes
This article is available in French at www.cmaj.ca/lookup/suppl/doi:10.1503/cmaj.191707/-/DC1
CMAJ Podcasts: author interview at https://www.cmaj.ca/lookup/doi/10.1503/cmaj.191707/tab-related-content
Competing interests: Sean Wharton reports receiving honoraria and travel expenses and has participated in academic advisory boards for Novo Nordisk, Bausch Health, Eli Lilly and Janssen. Sean Wharton is also the medical director of a medical clinic specializing in weight management and diabetes. David Lau reports receiving grants and research support from AstraZeneca, Novo Nordisk and the Canadian Institutes of Health Research (CIHR); speaker bureau fees from AstraZeneca, Bausch Health, Boehringer Ingelheim, Diabetes Canada, Eli Lilly, Merck and Novo Nordisk; and consulting fees from Amgen, AstraZeneca, Bausch Health, Boehringer Ingelheim, Gilead, HLS Therapeutics, Janssen, Eli Lilly and Novo Nordisk. Michael Vallis is a member of advisory boards for Novo Nordisk, Bausch Health and LifeScan. Michael Vallis has also received consulting fees from Bausch Health, LifeScan, Novo Nordisk and Sanofi, and speaking fees from Novo Nordisk, Sanofi, Bausch Health, Abbott and AbbVie. Arya Sharma reports receiving speaker’s bureau and consulting fees from Novo Nordisk, Bausch Pharmaceuticals and Astra-Zeneca. Laurent Biertho reports receiving grants from Johnson and Johnson and Medtronic, and is a member of advisory boards for Novo Nordisk and Bausch Health, outside the submitted work. Denise Campbell-Scherer has no personal financial relationships, but reports receiving research funding from the following sources in the past 3 years: Novo Nordisk Alberta Diabetes Fund (NOVAD), a peer-reviewed grant that is a partnership between the University Hospital Foundation, Novo Nordisk and Alberta Innovates joint funders; Alberta Innovates Health Solutions (Cancer Prevention Research Opportunity and Collaborative Research and Innovation Opportunities competitions), CIHR (Strategy for Patient-Oriented Research and Knowledge-to-Action competitions); Northern Alberta Family Medicine Fund; and the Alberta Cancer Prevention and Legacy Fund. She also reports receiving knowledge transfer funding from the following sources in the past 3 years: an unrestricted education grant from Obesity Canada, funded by Novo Nordisk Global; a Worldwide University Network Meeting Grant; an Agency for Healthcare Research and Quality R13 grant for a Healthcare Effectiveness and Outcomes Research; and a Physician Learning Program grant from Alberta Health and the Alberta Medical Association. Angela Alberga reports receiving the following grants: the Santé Award from Fonds de Recherche du Quebec, the Mitacs Accelerate Grant, and the Concordia University Start-up Team Grant, outside the submitted work. Jennifer Brown reports receiving nonfinancial support from Novo Nordisk, and personal fees from Bausch Health, Dietitians of Canada, Obesity Canada and the Canadian Association of Bariatric Physicians & Surgeons. Yoni Freedhoff is the co-owner of the Bariatric Medical Institute and Constant Health, which provide weight management services; Constant Health has received a grant from Novo Nordisk. Yoni Freedhoff is also the author of The Diet Fix: Why Diets Fail and How to Make Yours Work published by Crown Publishing Group, and receives royalties for the book. In addition, he is the sole author of the Weighty Matters blog and a column for Medscape and many other op-eds and articles in which he has publicly expressed opinions about the treatment, management and prevention of obesity. Yoni Freedhoff also regularly speaks on topics related to obesity and receives honoraria and travel costs and expenses for same. Michel Gagner reports receiving speaker honoraria from Ethicon, WL Gore and Medtronic; consulting fees from Novo Nordisk, Bausch Health and Lexington Medical; and holds stock options with Lexington Medical. Margaret Hahn reports receiving consulting fees from Alkermes. Marie-France Langlois reports receiving personal fees from Novo Nordisk, Valeant, Merck Canada, Sanofi, Eli Lilly and Boehringer Ingelheim; a grant from Merck Canada; and other fees from AstraZeneca and from TIMI (Thrombolysis in Myocardial Infarction) Study Group for diabetes clinical research as a principal investigator, all outside the submitted work. David Macklin reports receiving personal fees from Novo Nordisk and Bausch Health, outside the submitted work. Priya Manjoo reports receiving personal fees from Novo Nordisk, Bausch Health and Sanofi; and grants from Boehringer Ingelheim, Sanofi and AstraZeneca, outside the submitted work. Marie-Philippe Morin reports receiving speaker honoraria from Novo Nordisk, Bausch Health, Eli Lilly, Boehringer Ingelheim, Nestlé Health Science, Janssen and AstraZeneca; research subvention from Novo Nordisk and Sanofi; and consultation honoraria from Novo Nordisk, Bausch Health, Eli Lilly, Boehringer Ingelheim, Janssen and AstraZeneca. Sue Pedersen reports receiving personal fees from Novo Nordisk, Bausch Health, Janssen, Eli Lilly, Merck, AstraZeneca, Boehringer Ingelheim, Sanofi, Pfizer; grants from Eli Lilly, AstraZeneca, Boehringer Ingelheim and Sanofi; and nonfinancial support from Novo Nordisk, Bausch Health, Janssen, Eli Lilly, AstraZeneca, Boehringer Ingelheim and Sanofi, outside the submitted work. Megha Poddar reports receiving honoraria for continuing medical education (CME) from Novo Nordisk, Bausch Health, Boehringer Ingelheim, Eli Lilly, Jenssen, Merck, the Canadian Collaborative Research Network and the Antibody Network; education grants from Novo Nordisk and Bausch Health; fees for mentorship from Novo Nordisk; fees for membership of advisory boards from Novo Nordisk and Bausch Health; and a quality improvement project grant from Boehringer Ingelheim. Paul Poirier reports receiving fees for consulting and continuing medical education from AstraZeneca, Boehringer Ingelheim, Janssen, Eli Lilly, Novo Nordisk, Valeant and Bausch Health, outside the submitted work. Judy Shiau reports receiving personal fees from Novo Nordisk and Bausch Health, outside the submitted work. Diana Sherifali reports receiving consulting fees for advice regarding chronic disease and diabetes management from Merck, and a grant from Obesity Canada to support the literature review process, during the conduct of the study. John Sievenpiper reports receiving grants from CIHR, the Nutrition Trialists Fund at the University of Toronto, the International Nut and Dried Fruit Council Foundation, the Tate & Lyle Nutritional Research Fund at the University of Toronto, the American Society for Nutrition, the Glycemic Control and Cardiovascular Disease in Type 2 Diabetes Fund at the University of Toronto, the National Dried Fruit Trade Association, PSI Graham Farquharson Knowledge Translation Fellowship, the Diabetes Canada Clinician Scientist award, the Banting & Best Diabetes Centre Sun Life Financial New Investigator Award, the Canada Foundation for Innovation, and the Ministry of Research and Innovation’s Ontario Research Fund. Dr. Sievenpiper has received personal fees from Perkins Coie LLP, Tate & Lyle, Dairy Farmers of Canada, PepsiCo, Food-Minds LLC, European Fruit Juice Association, International Sweeteners Association, Nestlé Health Science, Canadian Society for Endocrinology and Metabolism, GI Foundation, Pulse Canada, Wirtschaftliche Vereinigung Zucker e.V., Abbott, Biofortis, the European Food Safety Authority, the Physicians Committee for Responsible Medicine, the Soy Nutrition Institute and the Comité Européen des Fabricants de Sucre. Dr. Sievenpiper has received nonfinancial support from Tate & Lyle, PepsiCo, FoodMinds LLC, European Fruit Juice Association, International Sweeteners Association, Nestlé Health Science, Wirtschaftliche Vereinigung Zucker e.V., Abbott, Biofortis, the European Food Safety Authority and the Physicians Committee for Responsible Medicine, Kellogg Canada, American Peanut Council, Barilla, Unilever, Unico Primo, Loblaw Companies, WhiteWave Foods, Quaker, California Walnut Commission, Almond Board of California, outside the submitted work. Dr. Sievenpiper is a member of the International Carbohydrate Quality Consortium and the Clinical Practice Guidelines Expert Committees of Diabetes Canada, European Association for the Study of Diabetes, Canadian Cardiovascular Society, and Obesity Canada, and holds appointments as an Executive Board Member of the Diabetes and Nutrition Study Group of the European Association for the Study of Diabetes, and as Director of the Toronto 3D Knowledge Synthesis and Clinical Trials Foundation. He is also an unpaid scientific adviser for the Program in Food Safety, Nutrition and Regulatory Affairs and the Carbohydrates Committee of the International Life Science Institute North America. He has a spousal relationship with an employee of Anheuser-Busch InBev. Sanjeev Sockalingam reports receiving honoraria from Bausch Health Canada within the last 36 months. Valerie Taylor reports receiving speaker fees from Sunovion. Shahebina Walji reports receiving consulting or advisory board fees from Novo Nordisk, Bausch Health and Takeda and speaker’s bureau fees from Novo Nordisk and Bausch Health. Shahebina Walji also reports selling Optifast Meal replacements through a weight management centre Optifast is a product produced and sold by Nestlé. No other competing interests were declared.
This article has been peer reviewed.
Contributors: All of the authors contributed to the conception and design of the work and the acquisition, analysis, and interpretation of data. All of the authors drafted the manuscript, revised it critically for important intellectual content, gave final approval of the version to be published and agreed to be accountable for all aspects of the work.
Funding: Funding for this initiative was provided by Obesity Canada, the Canadian Association of Bariatric Physicians and Surgeons, and the Canadian Institutes of Health Research through a Strategy for Patient-Oriented Research grant, with no participants or authors receiving any personal funding for their creation.
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