BMI stands for Body Mass Index. Your BMI is a number calculated from your weight and height that approximates the percentage of your total weight that comes from fat, as opposed to muscle, bone or organ.
The higher your BMI, the higher the percentage of fat in your body and risk of weight related disease and illness such as diabetes, high blood pressure and heart disease.
A BMI between 20 and 25 is generally considered a healthy weight for height; over 25 is considered overweight, and over 35 is considered obese. A BMI of 40 or greater makes you a candidate for weight loss surgery, or 35 with other health-related conditions.