Body fat is hard to measure directly. So, it is often measured by body mass index (BMI). 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.