It is recommended that you use two methods to stratify your weight and the risks to your health:
- Body mass index (BMI)
- Waist size
Note that these two methods do not apply to young people under the age of 18 or to pregnant or breastfeeding women.
It is important to remember that your weight alone is not enough to properly assess your risk for certain health problems, since many other risk factors exist. Please note that this article does not replace a consultation with a health professional.
What is the BMI?
The BMI, or body mass index, is used to assess the risk of weight on health. It does not measure the % of fat mass.
It is calculated as follows: (Weight (kg))/(Height (m) x Height (m)) = kg/m2
You can calculate it yourself at home by taking your weight and height.
1 kg = 2.2 pounds
1 inch = 2.54 cm (and 1 cm = 0.01 m)
Table showing the stratification of health risk, according to BMI:
|18.5 to 25
|25 to 30
|30 to 35
|Class 1 obesity
|Class 2 obesity
|Class 3 obesity
What are the risks of being overweight or obese?
- Type 2 diabetes
- High blood pressure
- Dyslipidemia (high cholesterol level)
- Heart disease (e.g., heart attack or infarction)
- Diseases of the gallbladder and liver (fatty liver)
- Sleep apnea
- Certain cancers
What are the risks of being underweight (too thin)?
- Decreased immune system function
It should be noted that being underweight can be secondary to an eating disorder (anorexia, bulimia, etc.) or to certain underlying health problems, such as cancer. On the other hand, some people with small builds naturally have lower-than-normal weight even if they are eating well and consuming enough calories. These people do not have an increased risk of health problems.
Is the BMI suitable for everyone?
BMI is not a measure that can be used for everyone. This is because it’s not suitable for those under the age of 18 or young adults who have not completed their growth, as well as for pregnant and breastfeeding women. The risk also varies from one ethnic group to another, with some having predispositions to certain health problems linked to obesity.
Also, the current BMI scale is not quite suitable for people 65 and over. It is estimated that for this class, a BMI slightly above that of the current healthy weight (18.5 to 25) would be more representative of normal weight.
Also, since it is based solely on total weight and not on body fat, it should be taken lightly for athletes and very muscular people. In fact, as muscles weigh heavily on the scales, a person with a perfectly acceptable percentage of fat could end up being overweight or obese, which suggests a higher risk of health problems, whereas on the contrary, a high level of physical activity is more beneficial. For this population, the use of the waist circumference better represents their risk.
The waist circumference takes into account the distribution of body weight. This is because fat accumulation in the abdomen carries a higher level of risk than fat accumulation in the thighs. The waist size measures this accumulation of abdominal fat.
Why is abdominal fat a problem? Fat that accumulates in the abdominal or visceral area surrounds vital organs. It promotes increased bad cholesterol, high blood pressure, type 2 diabetes and heart disease.
How do you measure your waistline?
- Get a tape measure.
- If possible, get someone take the measurement for you. This ensures a more accurate measure. If you’re alone, sit in front of a mirror.
- Find your waist - it's halfway between the lowest rib and the top of your hip bone
- Take the measurement. You should be standing and avoid bending over. Make sure the tape remains straight and parallel to the ground. It should be stuck to your skin, but not squeezing or pinching.
Waist circumference leading to increased risk varies according to ethnicity. In fact, some are more at risk of cardiovascular health problems, for example. In addition, the general constitution (like the average height) may vary. Here are the measures that lead to increased health risk:
|Country of origin
|Canada and the United States
|≥ 102 cm
|≥ 88 cm
|Europe, Sub-Saharan Africa, the Middle East, the Mediterranean
|≥ 94 cm
|≥ 80 cm
|Asia, Japan, Central America and South America
|≥ 90 cm
|≥ 80 cm
Health risk stratification
By combining BMI and waist circumference, you get a good idea of the risk that being overweight brings to a person. Note that from a BMI of 35, the waist circumference no longer provides additional information to stratify the risk, as the person’s risk for is automatically very high or extremely high.
Risk stratification for person from Canada and the United States:
Class 1 obesity
< 102 cm (H) and 88 cm (F)
≥ 102 cm (H) and 88 cm (F)
As mentioned earlier, other risk factors must be taken into account when calculating your total risk, such as the presence of high blood pressure, high bad cholesterol, diabetes, a history of cardiovascular problems, your diet, your level of physical activity, tobacco use, etc.
If you want to improve your lifestyle or lose weight, the following guides may help you: