Fat Cat - Need help!!

Well I would say you have a challenge here since 1 cat is fine and the other sounds, sorry to say, obese! Did Petey get a thorough health exam, there are certain conditions that can cause this such as irregular thyroid. Or do you notice Petey chowing down most of the food........
If all health considerations are cleared, for 1 they are being fed to much food. I would try an all natural diet, no meow mix, this will cut out additives that may contribute to weight gain. All natural foods are more filling and satisfying as well..........1/4 to 1/3 cup per day per cat, and if they are that lazy, tempt them with some toys!!!! Allow them to appreciate food, most vets say it's good for a cat to be hungry, not starved, but hungry.

Meow mix pouches are fine (the mm dry is horrible).

My suggestion is to elevate the food of the skinnier one (since the fat one will have a harder time reaching it) if him stealing her food is a problem. I wouldn't recommend any of the 'lite' varieties of food, simply because they put way too many carbs in which easily convert to body fat. I'd find a high protein, moderately high fat food. You can still cut his calories by just feeding LESS of this food.. Cats don't need 1c food a day for all foods (my girls only eat about 1/3-1/2 and one of them is/was 19 lbs). Depends entirely on what you feed though.

I agree, they are fat because you are feed them way too much. 1 cup a day, assuming you meant per cat is way too much plus wet food on top of that.

Just as a comparison, you can see even Meow mix pouch contains colors, fillers, additives, and does not offer the nutritional value of Natural Choice, for example......as well it is much more filling, they eat less.

Fillet Meow flavor pouch
Guaranteed Analysis
Crude Protein (Min) - 14.0%
Crude Fat (Min) - 1.8%
Crude Fiber (Max) - 1.5%
Moisture (Max) - 82.0%
Ash (Max) - 3.0%
Taurine (Min) - 0.05%
Ingredients
Tuna, Fish Broth, Tuna Liver, Beef, Guar Gum, Vegetable Oil, Carrageenan, Tricalcium Phosphate, Vitamins (Vitamin E Supplement, Thiamine Mononitrate, Vitamin A Supplement, Vitamin D3 Supplement, Menadione Sodium Bisulfite Complex (Source of Vitamin K Activity), Riboflavin Supplement, Pyridoxine Hydrochloride (Vitamin B6), Folic Acid), Minerals (Zinc Sulfate, Manganese Sulfate), Sodium Nitrite (To Promote Color Retention).

Nutro Natural choice pouch white fish and tuna
Ingredients
Fish Broth, Whitefish, Chicken, Chicken Liver, Tuna, Wheat Gluten, Beef Liver, Dried Plain Beet Pulp, Herring Meal, Dried Egg Product, Oat Fiber, Sunflower Oil, Flaxseed, Natural Flavor, Salt, Guar Gum, Menhaden Fish Oil, Potassium Chloride, Brewers Dried Yeast, Sodium Carbonate, DL-Methionine, Taurine, Sodium Ascorbate (source of Vitamin C), Vitamin E Supplement, Ferrous Sulfate, Choline Chloride, Zinc Oxide, Dried Chickory Root, L-Carnitine, Beta-Carotene, Thiamine Mononitrate, Copper Proteinate, Manganous Sulfate, Niacin, d-Calcium Pantothenate, Vitamin A Supplement, Vitamin D3 Supplement, Pyridoxine Hydrochloride, Riboflavin Supplement, Vitamin B12 Supplement, Folic Acid, Potassium Iodide, Biotin, Sodium Selenite.

Guaranteed Analysis
Crude Protein (min)\t8.00%
Crude Fat (min)\t4.50%
Crude Fiber (max)\t2.00%
Moisture (max)\t82.00%
Ash (max)\t2.50%
Linoleic Acid (min)\t0.75%
Calcium (min)\t0.18%
Phosphorous (min)\t0.16%
Magnesium (max)\t0.022%
Iron (min)\t50 mg/kg
Manganese (min)\t4.0 mg/kg
Zinc (min)\t77 mg/kg
Vitamin D (min)\t240 IU/kg
Vitamin E (min)\t60 IU/kg
Taurine (min)\t0.05%
Ascorbic Acid (min)*\t20 mg/kg
Docosahexaenoic Acid (DHA) (min)*\t0.015%
L-Carnitine (min)*\t30 mg/kg
Alpha Linolenic Acid (ALA) (min)*\t0.16%

Crude fats are burnt first, lower proteins are better for less active cats...

get rid of the meow mix and use a healther struvite prevention wet food like hills or royal canin. feed the wet food pouch half each in morning half in evening feed dry food half in morning and half in evening gradually reduce the amount of dry food. get it down to half a cup each if you can. be sure you stick around to make sure your little Petey isn't hogging all the food. if you can stretch the dry biscuts out to three meals that would be even better. let him work it off! see if you can find a lite formula or even a weight loss dry food. both hills, eukanuba and royal canin carry a weight loss food and give the rations for the size of your cat on the bag. be sure to base the rations on the size your cat SHOULD be not what it is. ask your vet for the healthy weight for your babies.

I would also play with them, make them run around and chase toys. Interactive 'wand' toys are great to get them moving.

Get them off a lite dry food.. way more carbs with less fat ...

In this case try the Natural choice indoor due to L carnitine to help with lean muscle mass and fat burning... Give more wet food and less dry ...

Meow mix is fine but the fat is very low

Is it the shredded they like or gravy so I can give some suggestions...

How old are they???

Lowering protein is Not a good idea ///

think of us .. eat a bowl of rice your hungrier than if you ate a few eggs.... rice is carb and egg is protein and fat

I also suggest taking them off lite food, as said above, it just has fillers to make them feel full but they burn off more quickly and the kitty then eats more because hungry.

If they do well on meow mix pouches, then feed them that, if you can get them to eat something better (and can afford it) then do that too, the more wet they eat the better.

Take 30 mins each day to make them unlazy and play with them.

Only feed the amount of food for what weight your vet thinks the cat should be and not what he is

Ask your vet what the right amount of food for your cat is. If cats loose weight too fast it is bad for their liver. Just a little info on my cats. My cats ( boys are 12 - 13 lbs & girl is 8.7) get 1/2 cup each of Nutro Natural Weight Managment. The problem I was having were the 3 Am wake up calls that I was giving into because I just wanted more sleep. My vets suggestion was that when they wake me up I should give them each a table spoon of wet food instead of the extra 1/8 cup dry. She said it's less calorie dense. Just remember to consult your vet.