[skrtskrt]

Yes absolutely, but you can just make the range wide enough to wash out the difference (like -2000 to 2000, summing to zero)

Then you would probably get more information from looking at the person thank you could from hearing a weight number that could be +/-2000 pounds

[XMPPwocky]

You could also do it modulo some number, I think?

Then knowing any individual number (weight + pad) mod n gives zero knowledge (I think. If all but one party reveal their pads, they can trivially determine the other's weight so it fails. Believe it to be secure if only 1 party is malicious, though. Cases for other numbers of bad actors are more complicated...)