BMI is a scale that uses a person’s height and weight to determine how slim or corpulent they are. It’s used to figure out how much tissue weighs. It’s a measurement used to see if a person’s weight is appropriate for their height. Based on where the number falls within the range, the BMI value is used to identify whether a person is underweight, normal weight, overweight, or obese. These BMI levels differ by region and age, and are frequently broken into subcategories such as very underweight and very severely obese. Being overweight or underweight can have major health effects, therefore while BMI is an imperfect approximation of a healthy body weight, it can assist in determining whether more testing or action is required.