The decision by Madrid's Fashion Week organizers to exclude models whose Body Mass Index is too low has been applauded around the world. But what is Body Mass Index, and how is it calculated? Is it really an accurate gauge of whether someone may have an eating disorder? The Eating Disorders Association has posted a short article about BMI and what is it.

"It can be a useful guide to both risk and recovery in adults, but is very much less helpful as an indicator in children."

The article gives a general range for healthy BMI in adults, and BMI that could be cause for concern.