Body mass index (BMI is one of the simple tools to understand whether a person’s weight is right for their height. It is a person’s weight in kilograms divided by the square of height in meters. It is an easy and inexpensive screening method to classify a person as being either underweight, normal, overweight or obese. According to WHO, a normal BMI for an adult is 18.5 - 24.9. A BMI falling outside of this normal range could be correlated with increased health risks. (BMI is interpreted differently for children and teens, even though it is calculated using the same formula as adult BMI. Children and teens's BMI needs to be age and gender specific because the amount of body fat changes with age and the amount of body fat differs between girls and boys.)

Carrying excess weight can increase the risk of certain chronic disorders such as type 2 diabetes mellitus, cardiovascular disorder, kidney disorders etc. On the other hand, having a BMI lower than normal can increase the risk of malnutrition, osteoporosis and anemia. 

However, we must be aware that this screening tool does not measure the fat content in the body. There are various methods to determine body fat such as skin fold thickness, body composition analysis, waist to hip ratio measurement etc. 

In the end, BMI is definitely a useful tool to identify the risk factors but since it does not take into account the level of activity and body composition, it can not be relied upon as the sole criterion for a healthy weight and therefore must be used with caution.

If you are concerned about your weight, it is important to consult a doctor or dietician to get a more complete understanding of your health so that you can take a holistic approach to weight management.