There is no reliable tool to assess a person's body size, but a combination of different measures can be used to diagnose overweight or obesity.
According to the World Health Organization (WHO), obesity is characterized by "an abnormal or excessive accumulation of body fat that can affect health". But how do you distinguish between obesity and overweight?
Weight alone is not a reliable indicator. In general, doctors use several tools, the first being the Body Mass Index (BMI).
We talk about overweight for a BMI greater than 25 and obesity from a BMI of 30.
Morbid obesity (which therefore has the most serious consequences for health) concerns people with a BMI of 40 or more. But this tool has its limitations: for example, the BMI does not provide any information on fat distribution. However, we know that having fat mainly in the abdomen increases the cardiovascular risk much more than an accumulation of fat in the hips and thighs.
This is why doctors also use waist circumference measurement to detect excess fat in the stomach. This is called abdominal obesity when the waist circumference is greater than 88 cm for women and 102 cm for men.
Another tool is the waist to hip ratio. It is considered high when the result is greater than 1 for men and greater than 0.85 for women.