Why is my cat suddenly starving?

[Rockbird]

18 month old spayed girl, not too fussed about food up till now and spends most of her time outside. Now suddenly she's starving, constantly meowing at us for food. She's gone from having one pouch a day and not especially being bothered about that, to four and wanting more. It's not the quantity of food that bothers me, maybe that's what she should be having anyway, but it's such a change for her.

Does she get dry food too?

Yes there's always dry food out but both cats pretty much ignore it these days. Boy cat's appetite hasn't changed at all. He's more of a home body in case it's relevant.

Maybe she used to eat at another house but they've moved or stopped and now she's having to eat at home again

Have you wormed her recently?

Take her to the vet. Increased hunger without weight gain can be a sign of hyperthyroidism (my cat has it).

Has she been going out a lot more? So more exercise, consequently hungrier. When was she spayed?
Tbh things that spring to my mind though, with a change as dramatic as from 1 - 4 pouches. My 2 girls, 3yo and 12yo, eat 2 pouches each and a bit of dry food / 24h and they're plump. I'd be concerned about a condition like overactive thyroid, or worms. I'd get her to the vet tbh.

Has she been wormed recently?

Mine always ask for more food during the cold weather. If it was warmer they would go outside - I think they are looking for entertainment.

She's due a worming. Definitely fatter, not huge but she was quite a dainty cat, all fur but now there's a lot more padding so it's not a case of eating without weight gain. She was spayed about this time last year, was a rescue cat scared of her own shadow so didn't really go outside until about Easter. Since then she much prefers to be outside even when it's pissing down. It's possible that she was being fed elsewhere I guess. She tends to stay quite local though, only our garden and the ones surrounding it. Doesn't go out the front AFAIK.

Sounds like a trip to the vet to rule out a few things anyway.