skinny puppy eats everything in site

Question
My 20 week old female Golden Retriever puppy only weighs 29 lbs and eats 3 cups of dog food per day (1/2 cup more than recommended). She always seems hungry. She has been tested for parasites, worms and both were negative. She has her nose on the ground always and eats everything she can get her jaws around: stones, plastic bags(pulled one from her butt the other day)leaves, dry grass, any junk etc etc. She has had bouts of diarrhea as a result and I watch her like a hog. Needless to say I need to keep her leashed at all times. Please advise, many thanks, "Maya's Mom!"

Answer
Unfortunately, much of what you describe is normal.  Start by evaluating her as in this link, http://www.longliveyourdog.com/twoplus/RateYourDog.aspx  If she really is too thin, feed her enough to bring her to ideal condition.  You may be used to seeing Goldens that people are shortening their lives by over feeding.  Although most dogs will thrive on most chows, there are occasional dogs that will do do better on a different chow.  I had a Lab a few year ago I had to feed almost twice as much as my other Labs.  He was also producing a larger, softer stool.  Since otherwise he was doing fine, I just fed him what it took.  If your evaluation of your dog shows it is on the thin side, and your vet agrees, feed it a little more.  

The one change I would suggest is switching to adult chow now.  That slows growth and allows more time to develop sturdy joints.  Along with keeping the dog lean, dramatically reduces joint problems in large breed dogs.

Foraging indigestables is a big problem with Goldens and other dogs.  A couple of years ago I attended a talk on Goldens.  The vet talked about all the things the clinic had to remove from dogs' stomachs, and what a mess bottle caps made of a dog's insides.  Problems can be far worse than the diarrhea.  Supervise her carefully.  Try to keep her relief area free of foreign objects.  
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.