BMI, or Body Mass Index, is used to assess health risks by measuring an individual's weight in relation to their height. It categorizes individuals into classifications such as underweight, normal weight, overweight, or obese, offering a general indication of potential health risks. While BMI is a useful screening tool for population-level assessments, it does not account for factors like muscle mass or fat distribution. Therefore, it is important to interpret BMI alongside other health indicators for a comprehensive understanding of an individual's health status.