Smudge has been getting Cosequin for a little over a year, mashed into his wet food twice a day, although he gets it to protect his urinary tract, not his joints.

As with humans, Cosequin (glucosamine/chondroitin) is a supplement, not a quickie cure. Its bioavailability (the amount a cat or human absorbs out of the amount they ingest) is low, so it has to become a routine part of the diet, and it's more for preventing further deterioration than repairing extant damage (although it does a bit of the latter as well).

If Cocoa's appetite is out of control, you can try giving him Vitamin E. Just puncture a capsule and let him lick it off your finger once or twice a day. It's totally safe for cats, and its only known effect is diminishing appetite. (Smudge says "and tasting really good.")