besity is a chronic disease characterized by the presence of excessive and/or dysfunctional adipose tissue that impairs health and wellbeing. Obesity increases the risk of serious chronic illnesses such as heart disease, cancer, stroke, diabetes and nonalcoholic fatty liver disease, among others. Obesity impairs an individual’s health-related quality of life and reduces life expectancy. In Canada, the prevalence of obesity in adults rose dramatically, increasing three-fold since 1985. Obesity, defined as a BMI ≥ 30 kg/m2, affected 26.4% or 8.3 million Canadian adults in 2016. Severe obesity (BMI ≥ 35 kg/m2), the fastest growing obesity subgroup, increased disproportionately over this same period. Since 1985, severe obesity increased 455% and affected an estimated 1.9 million Canadian adults in 2016. Overweight, defined as a BMI between 25 and 29.9 kg/m2, affected an additional 34% of adults in Canada (10.6 million individuals). Over the same 30-year time period, measures of abdominal obesity increased significantly, are more pronounced and are associated with significant increases in health risk.

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the increase in childhood obesity mirrors this adult trend. One in three children and/or youths between six to 17 years have overweight or obesity, an increase from one in four in 1978/79. The prevalence of obesity among boys, in particular adolescent boys 12-17 years, is significantly higher than for adolescent girls (16.2% versus 9.3%). The causes of and contributors to obesity are complex and extend well beyond an individual’s choice over calories in and out. Established contributors to obesity include socioeconomic status, sex, ethnicity, access to healthcare, genetics, regional food and built environments. Health professionals should not rely solely on BMI to predict an individual’s health risk but use it in conjunction with other screening and assessment tools. Weight bias, stigma and discrimination are pervasive in the healthcare system and society and result in the unjust treatment of individuals living with obesity. Obesity affects individuals, families and society. The economic burden is significant. In 2014, the global economic impact of obesity was estimated to be US $2.0 trillion or 2.8% of the global gross domestic product (GDP). In Canada, obesity and its related illnesses result in a large cost to society due to increases in direct (i.e., physician, hospital, emergency room use) and indirect costs (i.e., lost productivity, absenteeism, disability), estimated to be $7.1 billion in 2010. Successful management (i.e., prevention, management and treatment) of obesity requires collective effort at the policy, health system, community, and individual level. There is a need for continued and focused investment in research funding to support the scientific understanding of obesity. This includes non-experimental research on the biopsychosocial and environmental causes and contributors, and experimental research to develop and test interventions to prevent, manage and treat obesity. Research on how best to implement evidence-based practice and policy is a priority.