Feeding and appetite

Question
Labman,

My 10-month old Golden Retriever is constantly hungry.  I know that this is common for the breed, but I am starting to think that there might be a problem.  Each meal, he eats 2-cups of dog food in about 60-seconds max.  Whenever we are outside, all he will do is eat sticks, grass, dirt and try to eat rocks, shingle particles -ANYTHING that is one the ground.  If we are outside for 45 min, he will not chase a ball or play - he will eat for every second that we are outside.  Everytime we go outside, he grabs mouthfuls of grass/dirt to eat...even while going to the bathroom!  He rips toys apart to eat them (I know many dogs like to rip things apart, but he eats them.)  Like many dogs, he is obsessed with all paper products -- napkins, paper bags, cardboard boxes, toilet paper, he can't get enough.  He is also especially found of metal and tries to eat the central air vents, for example.  He is not overweight.  I have consulted the Purina site (with pictures) that you recommended to others and he is on the lean side.  How do you know the difference between feeding him more because he is truly hungry vs. a dog's insatiable appetite -- or could it be something else?  We cannot have anything within his reach.  I wouldn't be so concerned if he were just destroying things (like rugs and clothing) but he destroys them to eat them and they can make him  very sick.  He is 10-months and I think that he has all of his molars, so it shouldn't be teething, right?  Any advice?  Thanks so much in advance.

Answer
You could dump a can of green beans or pumpkin in his dish each meal.  It would fill him up without adding calories or anything else digestible enough to unbalance his diet.

Buy some sturdy chew toys.  

The pet stores are full of toys that many dogs will quickly chew up into
pieces they could choke on or cause intestinal blockages.  If you are not
there to watch, stick to sturdy stuff such as Nylabones and Kongs.  Keep a
close eye on chew toys and quickly discard anything that is coming apart in
pieces.  Rawhide is especially bad because it swells after being swallowed.
These problems are the worst with, but not limited to, large, aggressive
chewers such as Labs.

Ropes from the pets' store quickly turn to hazardous shreds.   Ones I made
lasted much better.   Go to a hardware or home center that sells rope by the
foot.  Buy 2' of 3/4" poly rope.   Melt the ends, and tie  knots in it.   Get
them as tight as possible, put it in a vise and pound it with a hammer.  Watch
carefully, and be ready to discard when it comes apart.

Glad somebody took the time to look at some of the questions here.