A very simple yet common barometer used to calculate a person's health related to their weight is the Body Mass Index or BMI. The BMI is a number derived from dividing weight by height squared. Based on your BMI number you fall under one of four general health classifications. 

The primary factor in the BMI is high body weight and obesity, a condition usually defined as a weight that is 20 percent above normal. If you use percent body fat to define obesity it amounts to being above 30 percent for women and 25 percent for men. A BMI score of 27 or higher normally indicates that there is a weight problem which may effect the individual's health.