Heart disease, diabetes and high blood pressure are all linked to being overweight. A BMI of 30 and over increases the risk of death from any cause by 50 to 150 percent. Just enter your height and your weight, and JavaScript can use a formula created by the Panel on Energy, Obesity, and Body Weight Standards to figure out your Body Mass Index. This index classifies you into one of several categories, from underweight to desirable to obese.