I would feed him more as well. Barley was 13 pounds at 8 weeks when we got him home - and honestly - he was always on the slim side. I fed him about 3 1/2 cups of food when he was a puppy. He is now over a year and 1/2 and is not quite a 70 pounds - and is very very healthy and gets lots of exercise - so looks lean and very strong. (Moby was always thicker and stockier as he was an English lab - so it is sort of shocking for me to realize that Barley weighs about the same as Moby did - but looks so much thinner.