I had a couple of female passengers who were quite uncomfortable about giving their weight & a chap who didn't know his,
It's sometimes possible to work backwards...."you are ok for this flight as long as you're under 17 stone."
Sometimes the answer is obvious, (I know, don't ass....u...me.)
Fat nacker brothers can cause concern.
In't there a video on youtube of an overweight cessna plunging earthwards?
http://youtube.com/watch?v=yaimogfse9c