A long time ago in a galaxy far, far away, I used fast acting insulin and extraordinary eating to put on size. And it worked, but in my case, I got a bit porky. Hitting PRs on the weights, but weighing in at 240 lbs. at 5’10". I was a scary beast, but couldn’t run a mile without having to stop and being completely out of breath. I probably did not use insulin as intelligently as I could have, but that whole experience spooked me away from it.