Cat losing weight

My 11 YO male cat has just had a geriatric blood panel done. Vet says it's pretty boring and he's quite healthy for his age. His eyes are bright, fur shiny, lots of energy, BUT he's losing weight although he eats well...and a great brand of food (Fromm's). No indication of hyperthyroid. He may have a food allergy which the vet is not that concerned with. Spine is quite bumpy.

Any thoughts????

Perhaps a switch to a good quality wet food would help. Kibble really isn't a great choice for cats: www.catinfo.org

Do you have a copy of the lab work?