Question on nutrition

Hi All - I have a soft coated wheaten terrier that is 16 weeks. When I first got him at 8 weeks his stools were just "ok" (pretty soft and squirmy). But as I slowly transitioned him to his new food, his stools became very mussy and some days diarrhea.

After some trial and error I found that an all lifestyles food which is low in fat and low in protein in one of the dog high end food stores that works great with him.

His stools are now fairly firm and formed and look normal. However he has not gained any weight in the past 3 weeks. He weights 15 pounds. Prior to this food he was gaining about 1 pound per week. When my vet saw him recently for shots he commented that he looked very healthy but he wanted to see some more meat on his bones.

I was feeding him exactly in accordance with the active puppy guidelines on the food bag - a little under 1.5 cups per day. I'm concerned about having him on a low fat and low protein diet because people have told me that puppies need higher fat diets.

However, according to the dog nutritionist at the food company, that is a bit of a myth and what really matters is the calories. Both the nutritionist and vet suggested increasing the food. Starting yesterday I am feeding about 2.5 cups a day and we'll see how that goes.

That being said, the dog acts like he is still very hungry after eating. He spends a fair amount of his time when out of the crate circling around the kitchen floor vacuuming it up for crumbs. The breeder had him on anytime feeding - just left a bowl out all day. So I think he knows when to stop eating. Yet he still goes through his feeding in record time and would keep going if he had the chance.

Other than this, he is a very happy, healthy and playful dog - plenty of puppy energy.

I am wondering what your experiences are with this and whether it is a concern to have a puppy on a lower fat and protein food. Or whether you agree with the nutritionist.

One option I am considering is slowly mixing in another line of food from this same company which is higher in fat and protein. Its concerning though that this may throw off his system and we'd be back at the diarrhea stage again possibly. But on the other hand, if I'm going to have to feed the dog nearly 2 times the recommended amount (seems we are on track for that perhaps) then I'll be going through this food quickly and that will get expensive.

I'd appreciate your thoughts on this. Thanks all!!