At 160lbs, you don't have anything to worry about.
I'm 5ft 7 and my bulk took me to 206.8lbs
I had no problems getting my class 1, but I'm sure mass and balance might get interesting in some of the smaller aircraft. I want to get bigger but I think sooner or later I'll have to stop for the reason you are worried about.
As long as you are clean and only taking supplements you won't be doing anything thats adverse to your health. Although be careful not to give yourself kidney stones by taking too much protein and creatine.
This place needs a bodybuilding thread! Well done sir for starting it
