The diagnosis of obesity is usually based on a physical examination and a patient history (i.e., eating and exercise habits).
A measurement called the body mass index (BMI) does not directly measure body fat, but it is a useful tool to assess the health risk associated with being overweight or obese. A BMI of 18.5 to 24.9 is considered within the healthy range. The BMI is calculated using kilograms (kg) and metres (m) instead of pounds (lb) and inches/feet. Keep in mind that 1 lb equals 0.45 kg and 1 inch equals 0.0254 m.
BMI is calculated as follows:
BMI = body weight (kg) ÷ height² (m)
Example: if you weigh 150 lbs (68 kg) and are 5’8″ (1.73 m) tall, divide 68 by (1.73 × 1.73), or 2.99. The result is 22.74, which is right in the middle of the healthy range.
Health Canada classifies BMI according to the associated risk of developing health problems:
|- BMI value||- Classification*||- Health risk|
|Less than 18.5||Underweight||Increased|
|18.5 to 24.9||Normal weight||Least|
|25.0 to 29.9||Overweight||Increased|
|30.0 to 34.9||Obese class I||High|
|35.0 to 39.9||Obese class II||Very high|
|40 or higher||Obese class III||Extremely high|
Calculate your BMI here:
*The above classification does not apply to people younger than 18 years of age, pregnant women, or breast-feeding women. For people 65 years and older, the “normal” range is higher, beginning slightly above 18.5 and extending into the “overweight” range.