Like L2H said, it's all diet. Your goal is to get bigger, but you don't want more fat, you don't want to put on more fat. Well, if you are, then you should reevaluate your diet. Everyone says you got to eat big to be big, this is true, but only to a point. The "eating big" does not applie to everyone the same. One guy may be able to eat 4000kcl/ed and 500g carbs/ed and stay fairly lean while adding muscle. Then there are guys like me, who if they eat this way, they do get bigger and stronger, but they inevitably get fatter too. From the sound of it, you need to back down the total kcl/ed and back down on the carbs...try eating a more balanced diet of the 3 nutrients.
On your kidneys, question, does it hurt when you pee?