Tiny cat is ALWAYS hungry - where to start?

I found my cat, Wilson, outside last Fall and wound up keeping him when I couldn't find an owner.  He had digestion issues (seemed like IBS), but that's been under control on Nature's Variety frozen raw and some high-quality canned foods for variety.

He has always been around 6.5 lbs, and has always had an insatiable appetite.  He will eat ANYTHING and everything - dry pasta, houseplants, anything he can get his paws on.  He sometimes gets up to around 7lbs. but drops back down pretty quickly.  He'll easily go through two cans of food a day, probably even more if we let him. 

We just moved so I'm still working on finding a vet, but as soon as I do - does this sound like hyperthyroidism?  Should I start with testing for hyperthyroidism, or somewhere else?  I've never had him dewormed or anything.  Previous vets have said he's most likely anywhere from 5ish - 10 years old.

Again, question for a vet, but are there thoughts out there on whether I should just give him as much food as he'll eat (within reason, spread out over time) or if I should keep it to a more reasonable amount?

Thank you!

I'm not sure about hyperthyroidism, but I also have a little guy who loves to eat. He's going to be 2 soon and very small for his age. He would eat anything and everything if he had the chance. He doesn't have worms. He is a bit hyper though, so I attribute that for him not being fat. I think he was the litter's runt, plus he isn't neutered yet either. He's the sweetest, loving little guy but man alive, he's a pig. I wouldn't over feed, because it's just not healthy.

You should probably get him checked out, just an exam for peace of mind though. In case it is something, you need to know.

If he's going to be 2 soon, it's definitely time to have him neutered.  If it hasn't happened already, his urine will start to smell pretty skunky.  That goes away when they are neutered.  Also, he will very likely calm down when he gets rid of all those sex hormones telling him he should reproduce, and then he will be calmer, happier, and eat less.

Thank you. Yes, I know he needs it and it will be done soon. Right now we're dealing with a bunch of vet visits and bills for our special needs boy though. I've also heard that they will be lazier and fatten up when they get neutered. I don't know if this may apply for the original poster as well

Getting lazy and fattening up totally depends on the cat, the diet fed and the amount of play/exercise they get daily. Yes, genetics plays into it some (just like for people.)

Wilson was already neutered when we found him (and declawed... don't even get me started!) and he certainly isn't lazy or fat!

I caved and have been giving him dry food today since I have some Nature's Variety Instinct limited ingredient on hand and he just seems so hungry.  I don't know what to do - he just cries and cries because he's starving and he's so skinny, but he's eating as much as a cat twice his size should be getting.  I'm holding out hope that he's just been under-weight and should be eating more anyway, but I have no idea.