Why the Body Mass Index formula is wrong

I've always been sceptical about the BMI formula that is used to classify people as being the correct weight, obese etc.

BMI = weight in pounds/(height in inches x height in inches) x 703

or

BMI = weight in kg/(height in m x height in m)

Recommendations:

Below 18.5 = Underweight
18.5 to 24.9 = Ideal
25.0 to 29.9 = Overweight
30.0 and above = Obese

This excellent post looks at some of the reasons why the BMI is not always right...

http://www.npr.org/templates/story/story.php?storyId=106268439&sc=fb&cc=fp