Started lifting at about 19, used to weigh about 133lbs at 5'9". Now at 24 I weigh between 180-185 still at 5'9". That's roughly a 50lb gain at least 80% of which was muscle since I can still see my abs almost as well as when I was 19. Never touched any sort of anabolics either. Genetics have a big role in it and I am not talking about how big you were before you touched a weight, response to training as well as finding the training that your body will respond to, are the biggest factors. One of the gyms I train at is a commercial gym (not many juicers), and 90% of the people that go there will always look the same because of how they train.
