Body mass index ( weight ( in kg)/height(meters) 2) is a straightforward measure of obesity. It is easily measured without any complicated instruments and tests. In the western world, a normal BMI is defined as below 25 and above 30 is classified as obese.
We are using a measure like BMI to understand if the person is at risk of developing complications associated with high-fat mass. However, BMI may not be an accurate measure of body fat for many people. For example, the BMI may be high for someone with a high muscle mass, but the fat mass may be low. Similarly, the relation between BMI and disease risk is different in ethnic populations like Asian Indians. Here we define obesity as BMI > 25 and normal as less than 23. Such assessments like body composition analysis( hyperlink to Inbody page) may be helpful in deciding the degree of body fat. So, although useful, BMI cannot be considered the best measure of obesity.