4.19.2023 Board Book

Box 1: 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: • Type 2 diabetes 3 • Gallbladder disease 4 • Nonalcoholic fatty liver disease 5 • Gout 6 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

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 guide line 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 pro fessionals. The guideline may also be used by policy-makers and people affected by obesity and their families. The guide line 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 recommen dations. Resource limitations and individual patient prefer ences 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. Box 2: Appetite regulation 20–23 • 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.

GUIDELINE

• Colon (both sexes) • Kidney (both sexes)

• Esophagus (both sexes) • Endometrium (women) • Postmenopausal breast (women)

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 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 circumfer ence has been independently associated with an increase in car diovascular 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 circumfer ence alone, particularly in those individuals with lower BMI. 30,31 In addition to BMI and waist circumference measurements, a com prehensive history to identify the root causes of obesity, appropri ate 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 psycho logical 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 circum ference measurements alone. 33,34

CMAJ | AUGUST 4, 2020 | VOLUME 192 | ISSUE 31

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