What is body mass index?
BMI or Body mass index is n indicator which is used to determine a person’s healthy weight range for their height. It can also be considered alongside waist circumference to assess the amount of central fat. BMI however, has a limitation that it does not take into account age, ethnicity, gender and body composition.
Why is calculation of Body Mass Index important?
An increase or decrease in BMI can have a significant effect on physiology at the cellular level. It helps to track if a person is underweight, overweight, or obese.
Calculation of Body Mass Index
Body mass index is a statistical index. It uses a person’s weight and height to provide an estimate of body fat. BMI can be calculated in males and females of any age, by taking a person’s weight, in kilograms, divided by their height, in meters squared, or BMI = weight (in kg)/ height^2 (in m^2). The number calculated is then the individual’s BMI number. However, it is important to remember that BMI is insufficient as the sole means of classifying a person as overweight, malnourished or obese. Example, in elite athletes and body-builders, an elevated BMI is related to their increased muscle mass and not to their health status, thus falsely increasing their BMI.
Classification of BMI as per WHO (World health Organisation) – Hispanic population
- Severely underweight individuals – BMI less than 16.5kg/m^2
- Underweight – BMI under 18.5 kg/m^2
- Normal weight range – BMI greater than or equal to 18.5 to 24.9 kg/m^2
- Overweight – BMI greater than or equal to 25 to 29.9 kg/m^2
- Obesity – BMI greater than or equal to 30 kg/m^2
Asian and South Asian population:
- overweight – BMI that ranges between 23 and 24.9 kg/m^2
- obesity – BMI greater than 25 kg/m^2
Related Tests and screening procedures-
When individuals are identified as an abnormal weight, the following testing can be one-
- A BMI greater than 30 kg/m2- lipid, thyroid, diabetes screening.
- A BMI less than 18 kg/m2: thyroid, metabolic panel, psychiatric screening for an eating disorder, and conditions of malabsorption should be done. For cases in which weight loss was rapid and unintentional, a cancer workup should also be done.
- For patients who have a higher BMI, dietary interventions and exercise interventions should be started and followed upon on a daily basis.