you cannot just make shit dissapear it's not possible and that is a fact, there is nothing inside the earth that is creating new molecules out of nothing, your bones and skin expand because it takes molecules from the food you eat and the minerals you take in and expands them, there is no such force that does that on earth.  The only way that earth's mass would expand is through the falling of particles from astroids and meteors and such, that is the only way, and that is such a miniscule amount that it makes no difference in the earth gravitational pull.  Also, there is relatively the same amount of water on earth now as there was when the earth was formed.  Slight amount of water evaporate and escape the earth's atmosphere but on a whole again there is not enough to alter the earth's gravity.