I've used IGF-1 while leaning out with a low carb diet, pinning post workout along with most of my daily carbs. I can't say I experienced much in the way of noticeable results. I got leaner and held on to LBM, but nothing over and above what I've achieved without it.
Now using IGF-1 while eating above maintenance with ample carbs, I did see some noticeable gains in strength and a quick few pounds of muscle. This is just my experience, other may have had more success while carbs were low.