Classification of Obesity is done on the basis of BMI. Body fat is hard to measure directly. Body mass index (BMI) is a tool that doctors use to assess if a person is at an appropriate weight for their age, sex, and height. BMI measures weight related to height.
A BMI between 18 – 24.9 is normal, BMI between 25 and 29.9 indicates that a person is carrying excess weight. A BMI of 30 or over suggests that a person may have obesity.