Cats are obligate carnivores. That means that they only eat meat - mice, birds, chipmunks, whatever they can catch. Their bodies are equipped to metabolize protein and fat for energy. Cats don't naturally eat grains. Grains are carbohydrates that are not processed well and are stored as fat. If you look at the ingredients on a bag of dry food, often you will see that corn is listed first. Cats that eat only dry food have a good chance of becoming fat. This is also true of the "light" dry foods. Corn, wheat and soy can also cause allergic reactions in some cats.
Canned food is about 70% water. Cats in the wild would get most of their water from their prey. Cats need plenty of water to stay healthy. You could provide water in bowls, but some cats don't drink enough to stay hydrated. Lack of sufficient water could result in a urinary tract infection, especially for the males.
Check the ingredients on the bag of dry food you use. Chances are some form of corn is listed first or close to it. Many canned foods also use corn as a protein source. I recommend that you change to the best food that you can afford. Some would say that the worst wet food is better than most dry food. I would say that is mostly true. At least your cat will get the water she needs.
I feed my cats a combination of canned and dry. The canned food I have chosen does not contain any grains. The dry also does not contain grains. Both of these foods do not contain fish. I do that because Daisy cannot digest it well (shhh...Diarrhea). I would love to feed them strictly canned, but with five cats, it is cost prohibitive.
Here is Jack and Baby sleeping in the Cubs bean bag chair: