Speaking in evolutionary terms, the domestic cat began as a desert animal and derived all the liquid in their diets from their prey. The hypothalamus in the cat has not evolved sufficiently. The average cat simply does not drink enough water to thoroughly support kidney function, etc (The hypothalamus controls thirst, hunger, and has myriad other functions). Additionally, cats are obligate carnivores and have NO nutritional requirement for grains. The best meal for a cat is a mouse, bird, fish or lizard, or the canned or homemade equivalent.
Practically speaking, any very high protein, grain-free canned food would suffice. There are many good brands. Look for very high MEAT based protein (not plant based), no grains, and very low carbohydrate (a small amount of fruit and vegetable ingredients can help supply vitamins, antioxidants, etc).
It is best to switch over very slowly in 2-3 weeks or so. Eventually your cat can be fed three meals per day, which can be one can to 1 and 1/2 (Tuna size) cans per day in divided doses depending on your cat's size.
Some cats find it very difficult to give up their dry food. It this case very slowly add water to a small portion of the dry food, beginning with one teaspoon of water sprinkled on food the first day, followed by two teaspoons of water the second day...etc. The trick is patience! Go very slowly and be persistent.
Dry food can be kept as a treat. A dry prescription dental diet is a good choice as a treat, especially if you cannot brush your cat's teeth. You may not need the hair ball treats once your cat is on a better diet, but regardless, hairball treats won't hurt.
An adult cat should eat 1/4 cup (if dry food) AM and PM. Just as we need to eat smaller portions, your cat should as well. There are prescription calorie control diets that can allow you to feed your cat more like 1/3 cup of dry or it's wet equivalent twice a day and still lose weight. Many people try to just feed their cat less. Few are successful with weight loss until they select a prescription weight loss diet, but either way, be patient. It will take months to see the great progress you can accomplish with your cat.
Dr. Cheng is so right I too believe in his words.
My kitty Nemo was so allergic to grains in most cat food brands that he nearly starved himself, we kept him going on chicken and canned milk for a year, while I tried every cat food avail. in my city...
Finally from information online I found another brand in a city 3 hrs away, its a Natura brand called INNOVA.EVO...its GRAIN FREE and chicken not chicken by-products. he took to it immediately and has been on it for nearly 5 years, he is healthy and normal weight and I free feed which I know I shouldn't, but he only nibbles a bit here and there, not a big eater all at once.. I finally talked my local pet store to bringing this one in and it really sells good....there are other good grain free brands out there I've found out, go to a large Pet Store and they carry all of them I can't remember all the names Orjen(?) and California Natural are a couple.
My other cat Sami also loved this food but he developed an allergy to chicken so I had to find another source of protien..and Duck seems to be working (skin lesions)..I get this from my Vet. MEDICAL allergy. I have not been to the city lately to look.
thx and good luck Peg
Does anyone know of a better Brand that has duck for ingredients?