Maybe this guy is the reason why amazon is pretty much banning print on demand books?

Most of the overweight people at my grandparents old folks home were in wheelchairs because they had had their legs amputated, due to diabetes.
So if they just weighed them, I dont know how BMI would work for that, would it use their old height or would you have to measure their new height, from their stumps to the top of their head?