Actually Sylday, the research was apparently done in a collection of Hospice worldwide. the weight of the bed was the deciding factor (this any matter expelled as blood or excrement would not effect the research. While the beds have been accepted by the scientific community as reliable they still dispute the findings.
Basically the research claims that at the point of death, all subjects instantlu l;ost 21 grams, whether they were a 50 stone whale or a skinny 7 stone weakling.
Of course there is a lot more to it than that and I'm not going to comment on its veracity. those are simply the answers to your question.