I have a cat, she was an astray I've had her since last oct at the beginning she was slim, but put on weight after a couple of months, two weeks ago when the weather changed I noticed she slept the entire day which I found strange, after a couple of days I noticed her stomach seemed sucked in when before she had a belly, she hasn't gotten any worse but still lies around all day when before she wanted to go outside or would follow me everywhere I went, I took her to the vet to get her vaccines up to date and had her tested for lukimia and the cat fiv and was all negative, they said that she looks healthy, but they didn't see her before, and as I'm writing this there she is laying on a mat I made for her can anyone give me any reason as to what's happening is she sick or just going through some changes. I don't want to loose her if I can help it. Thanks

Did you tell the vet specifically what your concerns were? I would go back to the vet and have some tests done. Unfortunately I don't think anyone can tell you what's wrong, all answers would be guesses as no one can see the cat or run any tests.

Let us know how it goes. Good luck.

two weeks ago when the weather changed I noticed she slept the entire day which I found strange,

When the weather changed... my cats have been lying around a lot too. They do it every summer. Even with the A/C on, just seems to happen. They even get mostly canned food, which has way more moisture, meaning they aren't as dehydrated as most cats, and they still lie around a lot more. And the one doesn't eat as much.

So that part, in and of itself, I don't find strange at all.

As for the weight -- first, I have to wonder from the way you describe it. A lot of cats are overweight. If by "belly" you mean something that sticks out as an obvious belly, they aren't supposed to look like that anyway. Their belly shouldn't be sticking out. From the top view, they should show a bit of a waist, just not so much that their backbone looks too bony. But if by "sucked in" you mean everything seems all hollow, like seriously too small, that's a different story. So it's hard telling what you mean, other than that many cats are overweight so people think that's the norm. And the vet said she "looked" healthy. (Not that I have great faith in a lot of vets, but they oughta know an underweight cat when they see one.)

But a cat also shouldn't suddenly lose weight. This may not be so sudden and you just haven't noticed. But if it was really that sudden, that might worry me. Even if she was overweight before, losing weight quickly still can be a problem.

I'm not quite sure if there really is a problem here or not. Certainly lying around with the weather change I don't find odd. Don't know about the weight loss. If you're that concerned, you can always go back, make sure you clearly describe the entire situation, and make sure they run a complete blood panel with CBC, and a urinalysis. If it were me, I'd probably keep an eye on her for a while and see if she really does seem sick in some way.