How do I fatten up my cat?

If I were you I'd somehow scrape up the money to take Bella to the vet's, Emmett. And very soon. It sounds like she's quite ill.

Souinds a lot like like an impacted hairball. Its common among Cooncats. A trip to the vet is in order to make her get some hairball treatment. This can be serious nd can cause a big cat like a coon to suffer organ failure.

Those symptoms could be kidney failure. If that is what it turns out to be, about all you can do is try to keep her comfortable and happy.

grab a lump of her fur and skin and pull a bit. Does it snap right back or is the skin flap slow to return to its shape?

GET TO THE VET--I HAVE 5 CATS AND YOU NEED TO BE ON TOP OF THE SITUATION AT ALL TIMES--ESPECIALLY WHEN A CAT IS LETHARGIC, NOT EATING OR DRINKING, AND HAS LOT WEIGHT. SCRAPE UP THE MONEY IMMEDIATELY OR GO SEE A VET AND WORK OUT A PAYMENT PLAN--THEY WILL HELP YOU. IF THEY DON'T GO TO AN ANIMAL SHELTER OR CAUSE ASPCA--OFTEN THEY CAN FIND A FREE VET CARE CLINIC. CAN COULD HAVE KIDNEY FAILURE, CANCER, OR EVEN A STROKE. PLEASE, IF YOU LOVE THE CAT WHICH CLEARLY YOU DO, TAKE THE BABY TO THE VET SO THEY CAN REHYDRATE IT--IT'S VERY URGENT--GO NOW!!!!!!!!! THANKS!

Not to appear that were yelling at you, the above post was asking for some medical attention for your kitty. I have 2 Maine Coons and they are both the most loving little guys. Id hate to see them deprived of a life because of my finances.

In the past, Id come home with some critter and Id always be in hock to a vet.(It was one of the reasons my fist wife left me).
Id since improved my finances a lot but I still have an "Account" with our vet.

Wehave a whole list of possibilities here and none of us are capable of helping you over the phone. I dont think it would be very loving or responsible to not intercede with somw professional help for your cat and rehydration requires a deft and trained hand.
Not doing anything will only result in a painful and short life for your cat(you seem to be genuinely concerned and you love your cat).
So, we cant help you , you need to take over the responsibility for your pets life. I wont be very sympathetic to your future posts if you choose to ignore our advice

I agree with the seriousness of this pet owner's animal's condition. I love all our animals, and yes, they are expensive. Obviously, after having a certain number of them, you must draw the line financially as well as emotionally. It's very difficult to take care of the many we have without making many sacrifices. In our case, we live on a farm and have other animals as well. They require constant care. (It was not my cats would were ill--they are all healthy).
I hope the owner's cat is still with us and he/she went to vet to get some care!