If you would slaughter a human how many kilos of meat would you have left ?
Pigs are generally regarded to be a pretty good anatomical analogue to humans. Pig's live weight is just what it sounds like - what it weighs when it's still trotting around. The "hanging weight" is what the carcass weighs after it has been slaughtered and cleaned (no more guts, just skin, bones, and meat), and the hanging weight of a pig should be around 75% of its live weight. Then there's cut weight, which is the weight of the edible meat after the carcass is broken down into market cuts and the unused bones and whatnot are removed. A 215 pound boar will yield roughly 105 pounds of cut weight meat.
It would depend on the size of the human. But on average most of the person's weight as bones don't really take a large percentage of the person's weight.
Given that the human body is 60% water you can determine the weight if dehydrated.