BMI or Body Mass Index is a useful measurement to help determine if you are overweight or obese. It is calculated from your height and weight (actually by dividing your weight in kilograms by the square of your height in meters). BMI is an estimate of your body fat based on your weight and height and how that compares to "average" people. The higher your BMI, the higher your risk for certain diseases such as heart disease, high blood pressure, type 2 diabetes, gallstones, breathing problems, and certain cancers.
Limitations on BMI Usage
For most folks, BMI provides a useful guage of their healthy weight, but it does have some limitations. If you are an athlete or have a muscular build, it may overestimate your body fat (it assumes the extra muscle weight to be body fat). On the other hand, it may underestimate the body fat in older folks or others who have lost muscle mass for some reason (it assumes a certain percentage of your weight to be muscle mass, and if you have lost that muscle, but still carry the weight, it will underestimate your body fat). Check with your doctor if you have questions about how to read your BMI.