I'm not talking about fuel that you need to get back, we're still at the "leaving Earth" case. The point is that you need, say, 1000 tons of fuel to leave the Earth. Your rocket then will weigh [weight of empty rocket] + [weight of payload] + 1000 tons. And it is this mass that the engines will have to push while ascending. Of course, the fuel gets spent as you ascend - by the time you reach orbit, your rocket is now 1000 tons lighter.