My "Snickers" is 12 years old and went through these same symptoms about a year ago.
She all of a sudden became very food agressive and seemed to never get enough.
She was looking very thin and her fur was no longer silky.
A trip to the vet and bloodwork did reveal she has Thyroid Disease.
Once placed on her Thyroid meds "which are NOT expensive" she made a complete recovery and is now a healthy senior cat.
Anytime your cat changes from their normal routine, eating, elimination or moods, there is definatly a reason that needs to be addressed.
Your vet is the prime authority in diagnosing your cat.
Best wishes to you and your kitty.
