The following article found on Google - there are many more.
The issue of passenger weights will raise it's head from time to time, quickly to be squashed by the airlines as increased standard passenger weights equates to fewer passengers that can be carried on a particular flight and resultant reduced profits. The manufacturers would be compromised as well - would not be able to make the claims they do regarding passenger numbers, range and performance. A BIG NO-NO!!!
I remember being told (hearsay?!) that an aircraft crashed in Africa some years ago due to the passengers being on a charter to a convention of gold dealers/traders. The passengers carried their gold on their person and each passenger was well over the weight limit. The aircraft crashed on take-off due to being grossly over-weight - can't find it on Google, but I'm sure it's there somewhere?!