Wish I could use myself as an example but I have enjoyed living a life of excess and still maintained relatively good health. From my experience it is possibly the overindulgence in red meat, saturated fat, wine, etc. and possibly some underindulgence in certain areas specific to the person that are the problem.

Given that I now have mild NAFLD and gall stones, hindsight is 20/20.

I can imagine doing a study has got to be difficult especially at the start you have the bias of those doing the study.