The main function of IGF-1 is to promote hyperplasia, which means that new cells are created into the muscle, as opposed to hypertrophy which means that the cells grow in size but not in number and is the process by which you grow bigger with steroids and weight training. Some users report fat loss and some others do now. I'm interested in it because of its hyperplastic properties.
Now, are you supposed to feel that hyperplasia in a couple of weeks? From what I've read, these cells still need to mature and get bigger which is a process that can take months.