The most commonly used measurement for obesity is "Body Mass Index" (BMI) and waist circumference measurement. BMI is calculated by dividing body weight (kg) by the square of height (m²). This value is independent of age and gender. However, the use of BMI is not accurate in children, pregnant women and people with very muscular muscles, so it should not be used. Health authorities have divided BMI values into groups as normal weight, overweight and obese.

Those with less than 18.5 kg/m² are considered Slim
Those between 18.5-24.9 kg/m² are considered Normal weight
Those between 25-29.9 kg/m² are considered Overweight
Those between 30-39.9 kg/m² are considered Obese (fat)
Those over 40 kg/m² are considered Severely (morbidly) obese