Senior cat losing weight.

Hello,

My cat is 11 or 12 years old (he was a rescue kitty I inherited, so I'm not entirely sure of his age). He is perfectly healthy--eats, drinks, still loves getting attention--except that he is much thinner than he used to be and his fur has lost some of its luster.. it seems a bit thinner than it used to. There have been no behavioral changes, except that maybe he is a little more vocal than he used to be. I recently moved into my own apartment, so he is alone more than he used to be and lets me know he is sad about that when I walk in the door.

A few months ago I brought him to the vet just for a check-up, and they gave him a full "senior wellness" exam that came back with no bad results. He had lost a couple of pounds, but no clear culprit...except maybe aging (and he had always been a big cat).

Essentially, my question is whether or not it is normal for cats to lose weight with age. His weight loss feels significant to me--I can feel his ribs and his "shoulder blades" when I pet him now, which I never used to be able to do. I don't have a scale though to actually measure his weight. So barring other symptoms, should I ignore the weight? I am really nervous and keep thinking about taking him back to the vet, but honestly am pretty broke right now and not sure I can afford to have him go through those tests again until about a month from now. I know you can't tell me whether or not I need to take my cat to a vet really, but I am wondering about "natural" weight loss...

Thank you,
Marie