I believe on close inspection of the photo of Justin I see the head, neck and torso are him, but you can tell the photoshopping took place at the waist just below the love handles area. My guess is the upper half is from a picture that he was in swimming trunks. He had quite a few shirtless shots on Malcolm in the Middle. Honestly, even though it is probably a fake, that is about how I would picture him in real life.