Could they do a blood test to check his thyroid? (to be sure) Cats with thyroid problems might need special diets as well (and I would hate to think we are telling you the wrong things to feed him)

If you buy the canned foods like friskies, 9-lives, you can almost always tell what consistancy they are. They may not be the BEST food around, but many cats prefer their taste over the so-called GOOD stuff. (don't we all??)