Number of Canadian adults who were obese in 2021, by province

According to the World Health Organization (WHO) and Health Canada guidelines, the index for body weight classification for the population aged 18 and older is: less than 18.50 (underweight); 18.50 to 24.99 (normal weight); 25.00 to 29.99 (overweight); 30.00 to 34.99 (obese, class I); 35.00 to 39.99 (obese, class II); 40.00 or greater (obese, class III). The population aged 12 to 17 is classified as "severely obese", "obese", or "overweight" according to age and sex specific cut-off points defined by the World Health Organization.

A systematic review of the literature concluded that the use of self-reported data among adults underestimates weight and overestimates height, resulting in lower estimates of obesity than those obtained from measured data. Using data from the 2005 Canadian Community Health Survey (CCHS) subsample, where both measured and self-reported height and weight were collected, BMI correction equations have been developed. This table presents obesity estimates adjusted using these equations.