The indicative tables below may serve as a benchmark

The food quantity depends largely on the weight and physical activity of the cat. Further factors are age, health condition, gene markers and metabolism. It should be borne in mind that domestic cats often don’t move a lot and their basic issue is overeating.   

The indicative tables below may serve as a benchmark. Besides the values shown in the table, it’s crucial to take into consideration your cat’s individual traits.

Cats should eat 15-20 calories per 1 pound (~33-45 calories per 1 kg) of body weight every day. The most canned foods’ caloric value is about 25-30 calories per 1 ounce  (~88-105 calories per 100 g), unless indicated otherwise on the package.

Wet food

Homemade food needs to approximate these parameters, by specifying that the meat content in the canned food is mostly up to 40 – 60 percent of its contents, and it might be more in the homemade food. A better proportion of the meat products would be more than 80 percent of the total volume of the food, whereby specifically meat should be the main part of them. It means more calories and adjustment of the portions if necessary.

Dry Food

Dry food is much more calorific than canned food. Assuming that its contents is 90-120 calories per 1 ounce (~320-430 calories per 100 g), the daily volumes based on the cat’s weight are as follows:

If the caloric value of the food is different, the volumes need to be changed as well. A constant intake of dry food isn’t the best option for your cat, specifically if loose food is concerned (you can find more on this topic you in the article “How to Choose Prepared Cat Food at the Shop”).

It’s good to divide food intake into several daily portions – normally 2 – 3 for an adult, and 5 – 7 for young cats.    Usually cats prefer to eat a few times during the day; some cats eat up the whole portion at once and other cats eat a handful of times. The food shouldn’t be constantly available to your cat, because this kind of diet easily leads to obesity.

Overweight

You’d best follow your cat’s condition, even if it eats theoretically enough amount of food. If it loses weight, increase the portions, which is true in the opposite event.    

The same applies to overweight cats, whereby you should consider the weight your cat is supposed to have and not in line with its current weight. In case of an overweight cat you must be careful when limiting the food that your cat eats, because if it eats less than 50 percent of its caloric needs over a long period of time, your cat might develop hepatic lipidosis.  

Neutered or sterilized cats are predisposed to diseases of the urinary tract, related to overweight, phosphorus and magnesium surplus. They need to eat more frequently in smaller portions and more energy-reduced food due to the reducing of their physical activity. Their metabolism slows and their appetite increases. Their mating instinct that otherwise expends a lot of energy comes in second and the amount of food remains the same.

Water

We should not forget that we must ensure a steady access to clean water for our cats. The amount of water your cat needs depends on its age, the type of diet and the ambient temperature. Insufficient intake of fresh and clean water increases the risk of urinary tract problems.

What should and what should not cats eat

Cats are predators and eat primarily birds and small animals in the wild. These are the ‘basic’ foodstuffs of their diet. Meat is the feline basic food and cats must get it also at home every day. Edible offal and fish are suitable foodstuffs, but they should be given less frequently. Plant foodstuffs are ‘supportive’ foods, they contain vitamins, are good for the digestive system, but cats don’t completely extract nutrients from them. Not all types of meat are equally suitable, some plant foodstuffs, however, are ‘unfavorable’ and you’d better avoid them. There are also ‘forbidden’ foodstuffs that could have unpleasant consequences.

References

Leighann Daristotle, Linda P. Case, Michael G. Hayek, Melody Foess Raasch (2011) Canine and Feline Nutrition: A Resource for Companion Animal Professionals,
45 – 117, 191 – 198

National Research Council, Division on Earth and Life Studies, Board on Agriculture and Natural Resources, Committee on Animal Nutrition, Subcommittee on Dog and Cat Nutrition (2006) Nutrient Requirements of Dogs and Cats, 22 – 28

Lisa A. Pierson, DVM, Cat Food Nutritional Composition — sortable charts, https://catinfo.org/docs/SortableCatFoodChartCatinfo.org2-22-13.htm

Kymythy R. Schultze, CN, Your Cat’s Nutritional Needs: The Basics, https://feline-nutrition.org/nutrition/your-cats-nutritional-needs-the-basics

Clinical Nutrition Team, Raw Diets: A Healthy Choice or a Raw Deal?, http://vetnutrition.tufts.edu/2016/01/raw-diets-a-healthy-choice-or-a-raw-deal/