Gaining/cutting

I know the thought of gaining mass while losing fat is considered near impossible, but what if you were only trying to get a certain body part to grow rather than your whole body.
my dilema is that i’m over weight but have a few lagging body parts, so i usually fart around trying to grow and lean. my right side is smaller because of a nerve palsy. i was kinda thinking of dieting and having my lifting directed at my weak spots rather than my whole body.i was also thinking of using androsol. could this help my lagging parts?