The Body Mass Index (BMI) is a measure which gives an indication whether someone has a healthy bodyweight, underweight, overweight or obese. The BMI can be calculated with the following formulae: The number that is calculated from one of these formulae can be looked up in the table below and determines if someone has a healthy weight or is nderweight, overweight or even obese.

BMI score Interpretation Complications <18,5: Underweight Underweight, low energy reserves 18,5-24,9: Healthy weight None 25-29,9: Overweight Increased risk for developing cardiovascular disease, high blood pressure, diabetes mellitus type 2, infertility in women, arthritis 30-34,9: Class I obesity Strongly increased risk for among others developing cardiovascular disease, high blood pressure, diabetes mellitus type 2, infertility in women, arthritis 35,0-39,9: Class II obesity >40: Class III obesity

Although the BMI can be a handy simple tool for determining if someone has a healthy bodyweight, it should be mentioned that the BMI depends only on bodyweight and length and is based on a person with average muscle mass. When someone has a larger than average muscle mass, this person will be heavier and consequently will have a higher BMI. This can lead to classifying this person as overweight, even when there is no increased risk of the complications mentioned in the table above. Most of the complications mentioned in the table, are caused by an increased fat mass, while an increased muscle mass can even decrease these risks. The BMI does not discriminate between muscle mass and fat mass, therefore the BMI is not the best method for determining if someone has a healthy bodyweight or has increased health risk.

References:

-World Health Organization BMI