Xenon BMI-THR Calculator descriptions Now you can quickly find out your Body Mass Index & your Target Heart Rate all in one tiny program. 100% freeware keep this little charm around to monitor your health & help get back in shape! Description of BMI from Medizine. com: When it comes to health risks the amount of fat you carry is more important than how much you weigh. The Body Mass Index which looks at weight in relation to height is a good indicator of excess body fat. A healthy BMI is between 19 & 24. 9 & obese is 30 or greater.