Map of Simcoe Muskoka

Body Measures

Body Measures

Body Mass Index (BMI) is calculated by dividing a person’s weight (in kilograms) by the square of their height (in meters). BMI is currently the best available measure at the population level to assess weight; however, there are limitations to its use.

Body weight is the result of a complicated set of factors, including biology, behaviours, income, society, and the environment. Engaging in health behaviours, such as eating well, being physically active and getting enough sleep, supports physical and mental well-being in people of all shapes and sizes. Healthy eating and physical activity are important for health, regardless of weight or BMI. 

At a population health level, BMI may be used as part of surveillance efforts to track body weight patterns over time, and potential level of health risk associated with weight. The Ontario Public Health Standards require epidemiological analysis of surveillance data relating to healthy weights (typically collected using BMI). Surveillance data should not be used as a measure of individual health status. Healthy weights are individualized and that health behaviours are important regardless of BMI.

BMI should only be used to assess weight, not health, at the population level.  It is not intended to assess weight or health at an individual level. There are many other factors (nutrition, physical activity, smoking, alcohol and substance use, blood work results, and blood pressure) that should be considered when assessing health. 

An individual can be classified as overweight who is active and be healthier than another individual classified as “normal” weight but who is sedentary.  Additionally, body type and muscle mass can result in misclassification. The term “obesity” medicalizes normal human diversity, contributes to weight stigma and hence, can inherently cause harm. While many serious and costly chronic health conditions have been associated with obesity, the cause-and-effect relationships of obesity are complex and not completely understood.

Significant health improvements and improved management of chronic diseases are associated with improvements in lifestyle behaviours independent of weight loss.  Furthermore, individuals classified in the obese weight category may be metabolically healthy while others at a “normal” weight may have elevated risks (e.g., high cholesterol, high blood pressure, elevated blood glucose).  This suggests that placing the focus solely on weight rather than other indicators of health can be misleading. 

This HealthSTATS section has data on the following: