For a cat of ideal weight, there is a layer of subcutaneous fat over their ribs which provides padding and insulation. But the fat should not so thick that you can’t feel her ribs as individual bones. So it is okay to be able to feel your cat’s individual ribs. However, if you can see the ribs as well it indicates that your cat is underweight.
The question is asking in a roundabout way whether their cat is underweight. The test mentioned above is a good one. Another test is to look at your cat from above to see if their is a well-defined narrowing of the cat’s body towards the hips as shown in the illustration.
If your cat is carrying too much weight you may have difficulty feeling he ribs. If there is a belly flap wobbling around as she walks this is normal even for a cat with perfect weight. It is not a sign of obesity. My cat is slender and he has a very distinguished belly flap. It provides him with a hint of the wild cat. They say that the belly flap makes a cat more flexible which allows them to run faster.
If you have doubts about your cats weight, your veterinarian would be pleased to advise. Cat guardians can also be concerned by being able to feel their cat’s shoulder blades. This is also normal. They do stick out a lot particularly when domestic cats are sitting upright on their bottoms like an Ancient Egyptian cat statue.
Illnesses often cause underweight cats and overeating can cause overweight cats. Being underweight is a very generic symptom of a sick cat because they have lost their appetite as they feel ill. Other symptoms should confirm the illness. Cat owners should be alert to obesity creeping up. It is very obvious and easy to fix provided the owner is being objective in their assessment and not blinded by their own obesity.