Body weight alone may not be the best parameter to assess one’s health. For instance, two people of the same age may have the same body weight but may not be equally healthy. For a person who is tall, a certain weight may be normal, whereas the same weight for a short person may be problematic. That is where Body Mass Index comes into the picture.
Body Mass Index (BMI) is an estimated measure of your body fat. It is often used by healthcare providers as a tool to evaluate your body mass to evaluate any risk factors associated with high body mass, like diabetes, hypertension, heart disease, and stroke. BMI is not an accurate measure of how fat an individual is and is only a rough estimation of health.
Your body mass comprises your muscles, fat, bones, and all your internal organs and components. BMI uses the ratio of your total body mass to your height as an estimation of your body fat content. This helps give an approximate idea of whether you fall in the healthy weight range or not. Healthcare providers use BMI as a screening tool to assess the likelihood of developing other chronic metabolic conditions.
You can find out your Body Mass Index by using a BMI calculator, such as the one available on the Centers for Disease Control and Prevention’s website.
You have to ensure the parameters are in the correct units. Enter your weight in kilograms and height in metres, or weight in pounds and height in feet and inches.
Here is the revised range of reference of BMI for a South Asian population for you to understand if you are at a healthy weight or not.
Body Mass Index
Less than 18.5
18.5 to 22.9
23 to 24.9
Obesity Type 1
25 to 29.9
Obesity Type 2
More than 30
Having a BMI less than 18.5 may indicate that an individual is more prone to the following.
Nutritional deficiencies of specific vitamins and those disorders
Poor immunity, and therefore frequent illnesses
Poor bone health
A higher BMI puts one at more risk for the following.
Hypertension (high blood pressure)
Bone and joint issues
Gastritis & reflux disease
Polycystic ovarian syndrome
Certain types of cancer, like gallbladder, colon & breast cancers
BMI is not an accurate tool for risk assessment. There are multiple other factors that have established direct causative relation to the above disorders that take precedence over BMI. Here it is only used as a screening tool. Not every individual with a high BMI has a high body fat percentage.
There are several conditions in which BMI may not be an accurate measure. Here are some reasons why.
BMI uses total body mass in its calculation. It does not differentiate between muscle mass and fat mass. Therefore, individuals who have a high muscle mass (athletes, body builders, physical labourers, etc.) who weigh more may be extremely fit but may still have a higher BMI. This however does not mean that they are unhealthy. In such cases assessing other simple parameters such as waist circumference and waist-to-hip ratio may be helpful.
It cannot and should not be used as a measure of health status in children, teenagers, and adults over the age of 60.
The reference range for BMI was made using European men as a standard. Therefore it is not an accurate range of measurement for women and people of non-European origin. This is particularly seen when applying this to African populations who can often be termed overweight or obese when in perfect health.
It cannot be a determinant of health during pregnancy.
It should not be used in those adults who have medical conditions that result in muscle wasting or atrophy.
BMI does not take into account the distribution of fat mass in your body, as it measures total body mass. Hence it cannot be used for those with increased fat masses in a particular region (like abdominal obesity) as a reliable tool.
BMI calculations for tall people and those of short stature have a larger margin of error, and cannot be reliable estimations.
BMI does not account for genetic and family history of chronic conditions. Hence people who have a normal BMI can still be susceptible to diabetes, hypertension, etc. It is therefore not an absolute tool and should not be treated as one.
BMI is a good screening tool as it is convenient and requires only weight and height. However, the results are not absolute and should be interpreted with knowledge of other background findings and medical history.
On average, people with a healthy weight and BMI are less likely to develop metabolic conditions like diabetes, hypertension, and heart disease in the long run. They are also less likely to get chronic joint pain and have better sleep.
If your BMI is higher than the normal range, your doctor may suggest that you lose weight (especially if you have weight around the abdomen). This can be achieved by eating sufficient fruits, vegetables, and protein, regular exercise including both cardio and strength training, and a regular sleep schedule.
If you are underweight, you may need to take a close look at your diet and assess if you are eating enough. You can gain weight in a healthy manner by introducing more complex carbohydrates and protein rather than opting for saturated fats or desserts. Strength training may also help.
Disclaimer: The content on this page is generic and shared only for informational and explanatory purposes. Please consult a doctor before making any health-related decisions.