I don't know about this. It's not like mentally retarded people are braindead plus there is a range of how functional they are. I'm sure some or many of them know enough about too much food = fat and still enjoy stuffing their maws just like regular butterballs do. I know they are predisposed to weird, stunted bodied and chub but that's one hell of a gut on the one on the left  and I don't believe he was forcefed the food that got him there.