Used and timed properly, slin can even tremendously help you lose bf... remember what it does: lower your blood glucose level... and when it's low enough, your body has no choice but release fat from your adipocytes.
Sure you'll flirt with hypoglycemia, so you better know what you're doing and have your share of experience with it already, but saying blatantly "slin will make you fat" is just false... slin with low/no carbs WON'T fatten you, GH or not... quite the opposite actually.
But then again, you must know exactly how to manipulate your diet, and be particularly cautious.