Why don't they do beginner, intermediate and advanced classes? That way the instructor can move the fit people up to the intermediate and advanced classes and keep all the obese and overweight people in the beginner classes until they lose the pounds. From what I understand and have witnessed, they can't do the poses properly unless they lose the weight, so they'll never advance to the next level. Unless they become normal sized. Meanwhile all the fit and normal sized people will be with their peers.