IGF-1 is very big factor in growth, but the IGF we can take-- LR3-igf-1-- is junk. You will get some leaning, thats about all. It had high hopes as did SARMs S4 when they both came into the spotlight but overall both have been dismal failures.
The best recipe for growth and utilizing endogenous production of IGF-1, is testesterone/GH/slin stack. We just cant take IGF directly for a whole host of reasons, mainly its extremely short half-life