Pro hormones would be my guess. The hardness he has in his forearms and arms can come from a strict diet, cardio, and pro hormones will give that low level thickness. He's used very little, probably played around with some stuff for the first time going into that show would be my guess. Definitely obtainable naturally. I'd need to see more pics, but he's very new to his pro hormone/gear use and using low doses at best.