Is my cat too thin?
by KittyKondo.com 

     Some cats are just naturally slim or perhaps have a high metabolism which allows them to burn food and fat faster. But how can you tell if your cat is too thin? Place your hands on the mid-spine of your cat and gently rub up and down to and from the rib cage. You should be able to feel a thin layer of fat before you feel the bones. If you can't feel a fatty layer then your cat may be too skinny for his or her own good.

     If your cat is thin because he eats little or no food you should take kitty to the vet in case there may be any underlying diseases or infections that need prescription medication. But, if your cat eats normally and uses the litterbox regularly you can add cat food rich in meat or try mixing in canned food with dry food to help gain weight.