Trouble is fuel water and food have to matter -- what if you're carrying canister stove, so you have canisters - then you have to allot for the weight of the empty canisters... so it's
a bit iffy not to include.

I think you just need to be completely honest about what you are carrying and for what trip, me, I just weight the pack loaded up with water and consumables. Getting into 4 different kinds of weights just sounds like an exercise in chestbeating to me <img src="/forums/images/graemlins/wink.gif" alt="" />