He has a stocky body so I have a hard time telling if he's heavy or not. It was easier with Ronaldo and Ronaldhino.
The guy's played a lot of high level games since a young age and it may be that he's closer to the end of his career than a man his ought to be (I worry that the same will befall Neymar, who seems to be playing non-stop despite his tender years.) The body can only give so much. Torres plays like an older man, that's for sure.