I. Defining Obesity as a Chronic Disease
Obesity is recognized as a complex chronic disease. It is characterized by abnormal or excess body fat (adiposity) that impairs health, increases the risk of long-term medical complications, and reduces lifespan.
Key Measurements and Classifications
Body Mass Index (BMI): Calculated as weight (kg) divided by height squared ().
Overweight: BMI .
Obesity: .
Class I: BMI .
Class II: BMI .
Class III: .
Severe Obesity: Defined as a (includes Class II and III).
Waist Circumference (WC): A proxy for abdominal adiposity. Thresholds for increased health risk:
Men: (40 inches).
Women: (35 inches).
Edmonton Obesity Staging System (EOSS): A five-point system (0–4) that examines comorbidity and functional status. It predicts mortality independent of BMI and is a valuable clinical screening tool.
II. Canadian Epidemiological Trends
The prevalence of obesity in Canada has risen dramatically over the last 30 years.
Three-fold Increase: Since 1985, the prevalence of adult obesity has increased by 300%.
Current Impact: In 2016, obesity affected 26.4% (8.3 million) of Canadian adults.
Severe Obesity Growth: This is the fastest-growing subgroup, increasing 455% since 1985.
Abdominal Obesity: Measures of waist circumference are increasing more pronouncedly than BMI trends, which is concerning because it is associated with higher health risks.
Regional Variation: Obesity prevalence is highest in the Atlantic Provinces and lowest in British Columbia and Quebec.
III. Health Consequences and Risks
Obesity reduces life expectancy by 6 to 14 years.
1. Medical Complications
Cardiovascular: Increased risk of heart disease, stroke, and hypertension.
Metabolic: Higher risk of Type 2 diabetes, non-alcoholic fatty liver disease, gallbladder disease, and gout.
Cancer: Roughly 20% of all cancers are attributed to obesity. It specifically increases the risk of colon, kidney, pancreatic, post-menopausal breast, and endometrial cancers.
Mechanical: A nearly three-fold increase in the risk of osteoarthritis and impaired mobility.
2. Psychosocial and Mental Health
Individuals with obesity are twice as likely to be diagnosed with a mood disorder.
Weight bias, stigma, and discrimination are pervasive in the healthcare system, leading to health inequalities and avoidance of care.
IV. Complex Causes and Contributors
Obesity is not simply a matter of individual choice or “calories in vs. calories out”.
Environmental & Energy Balance: While calorie intake has decreased and leisure physical activity has increased in Canada, other factors promote weight gain. These include chronic stress, insufficient sleep, and “energy-saving conveniences” (cars, remotes).
Iatrogenic Factors: Many medications used to treat obesity-related comorbidities (depression, hypertension, diabetes) actually promote weight gain.
Socio-Cultural Factors: * Indigenous Populations: On-reserve First Nations adults report higher obesity rates (36%) than Inuit or Métis populations.
Income & Sex: Income and education are inversely associated with obesity in women, but income shows a positive relationship with obesity in men.
Ethnicity: South Asian and Chinese populations have lower obesity rates than white populations, but they face increased cardiometabolic risk at lower BMIs.
Clinical Pearl: Do not rely solely on BMI to predict health risk. Some individuals with elevated BMI are “metabolically healthy,” while others with lower BMIs (particularly in certain ethnic groups) may be at high risk.
