The European Statistical Office uses the Body Mass Index (BMI) for weight calculations. That means dividing one's weight in kilos by one's height in metres squared. If the result is below 18, the person is severely underweight. If it is between 18 and 20 he or she is underweight. The person with a BMI of between 20 and 27 is normal, but overweight if the index is between 27 and 30 and severely overweight if his or her BMI is over 30.