What is BMI and which BMI is ideal?
Body mass index – abbreviated BMI – is a parameter that helps to determine whether weight and height are in a medically healthy relationship with each other, or whether the person is, for example, very overweight, that is fat. The World Health Organization (WHO) divides BMI into six different classes:
- Under 18.5: Underweight
- 18.5 – 24.9: normal weight
- 25 – 29.9: overweight/pre-obese
- 30 – 34.9: Obesity (obesity) degree I
- 35 – 39.9: Grade II obesity
- Over 40: Grade III obesity
The ideal weight that must be aimed for individually, however, also depends on age, sex, existing diseases and other information. The waist-to-hip ratio should also be considered. Your doctor will help you determine the right weight for you.
How do I determine BMI?
BMI is calculated using the following formula:
Body weight (in kilograms) divided by height (in meters) squared.
An example of a calculation should make this formula clearer: A person is 1.70 meters tall and weighs 80 kg.
The calculation to determine BMI is then: 1.70 x 1.70 = 2.89
Now divide the weight by this value: 80 / 2.89 = 27.7
27.7 – or 28 rounded up – is the person’s body mass index (BMI).
Waist circumference and waist-to-hip ratio instead of BMI
Body mass index only allows a first rough assessment. For example, if you have a lot of muscle mass, you can have a high BMI without actually being overweight. BMI also does not say anything about the distribution of body fat. Excessive abdominal fat is considered a particular health risk. There are other classifications that include age and gender in the assessment. For example, metabolism and body composition change with age.
Many experts now consider the value “waist circumference in centimeters divided by height in centimeters” (Waist-to-Height-Ratio, abbreviated WHtR) to be more meaningful. A value below 0.5 (in the case of the elderly below 0.6) is considered desirable. Waist circumference alone also helps as a rough guide: it should be no more than 102 centimeters for men and 88 centimeters for women.
Does the BMI calculator also apply to children?
Children have their own rules. There are special BMI tables here and the BMI can only be taken as a guide here as they are still growing. If you have the feeling that your child weighs too much or too little, it is best to talk to the pediatrician about it. In no case do not simply put the child on a diet.