That's assuming everyone stores fat in the same place....he may store fat in his arms quicker than elsewhere....I've seen all kinds of disproportionate fatties skinnier upper body, fat ass, thighs, cankles pear people then you see those skinny legged light bulb people and then there are the Jabba the Hutts....usually you get them on the belly if its from being overweight not on the arms and the chest, his upper belly looks clear, im thinking his belly looks fine, i would like to see a pic to confirm, but the way only his chest and arms have these marks tells me that it most likly muscle gain. does op have any other pics ?