We have now had Archie on a new food for the past 3 months, and what a huge difference it has made.
We did have him on Royal Canin, which is a good food, but decided to change him over to
http://www.bluebuffalo.com/cat-food/wilderness-indoor .
He is now a solid 15LBS of muscle, his energy level has gone up (not that it was really down).
His coat is unbelievably soft, hardly loses any hair at all, and his coat looks like he is covered in silver star dust, he just shimmers and shines when he moves.
He is not strictly an indoor cat, but we went with the indoor recipe because he spends 80% of his time indoors, he does get outside everyday, but only on harness and leash.
I am truly amazed at the change in Archie since we changed his food, we were told to use this food by 4 different breeders that I called, and what they all told me would happen with Archie, has absolutely happened.
I don't know how many of you use this food for your cats, or if it is even available in your area, but if it is, I can tell you that it really does work and has made Archie such a nicer looking cat as well as more muscular.
He still looks nice and lean, but very well muscled.