How to thicken wrists and body without gaining total fat?

Ok. So basicially i want to be less skinny without gaining total fat. Im mostly focusing on wrists because thats where i find it most annoying. DONT SUGGEST EATING please! my mom smoked weed when i was little. theres no chance on how eating can put on some serious weight for me. Working out is somewhat and option. i have gained only 5 pounds so far. Is there any workout to thicken wrist? because ive worked forearm and its big. i mean like wow. but my wrist changed none in size which makes it look smaller because of how big my forearms are. im trying grip strenght. anyways. any ideas?