My cat, who is now about 14 years old and still pretty active, is always hungry, no matter how much we feed her. She's really skinny too, she's been de-wormed but it hasnt seemed decrease her hunger at all.
Hi, I've had cats for over 30 yrs. I've had 2 cats that were over 10 yrs old that were eating a lot and were skinny and they were hyperthyroid I bet that's what's wrong with your cat. Get the vet to check his thyroid levels.
At 14 there's a possibility that she's developing one of the conditions that makes it difficult for kitty to properly process vitamin/mineral/protein content of food.
Does she seem healthy otherwise? I'd take her in to be sure. Also, if you only used an OTC wormer, they don't kill every type of parasite. You'll need a vet to tell you for sure.