All cats, from tabbies to tigers, are obligate carnivores, meaning they must consume meat to function. Because cats are apex predators and evolved to be hunters, they must eat animal meat to thrive. Read on to see how this translates into your feline friend's ideal diet.
There are many different cat breeds, so individual needs differ greatly. Accordingly, your cat's exact needs depend not just on breed, but also on her size, age, and usual activity level. You'll need to ask your vet for guidance about your cat's specific requirements.
Generally speaking, fully grown adult cats require between 24 and 35 calories per pound per day to maintain a healthy weight. Neutered or spayed cats also require fewer calories than their intact counterparts. The Animal Medical Center of Chicago has a useful chart for quick reference here.
Kittens have special nutritional needs because they double their weight every week for their first several weeks of life. After they have been weaned from their mother and moved to cat food, they require about twice as many calories as adult cats until they too reach adulthood.
Why Cats Need Meat
Cats in the wild exclusively eat meat. They need certain vitamins and minerals their bodies don't produce naturally, and they also lack the mechanisms humans have that allow us to get protein from plant sources. Some of these needs include Vitamin A, niacin (an essential B vitamin), arginine, taurine, and arachidonic acid.
Arginine is an amino acid critical in eliminating protein waste buildup. If this waste is not broken down and cleared away, it can lead to disastrous health effects. For cats, the only source of usable dietary arginine is in animal tissue.
Taurine is another amino acid only produced in body tissue. It keeps the heart and retinas working properly, and it also aids in the creation of bile necessary for digestion and waste management. Cats lack the ability to produce taurine themselves, so they can only get it by eating other animals.
Arachidonic acid is an essential fatty acid for fat storage and energy production. Cats lack the liver enzyme to produce the chemical themselves, so they must obtain arachidonic acid by eating animal fat.
Proteins, Fats, and Water
Like most animals, cats need special nutrients to keep their bodies healthy. The most important of these is protein, which is needed for "the manufacture of antibodies, enzymes, hormones, and tissues and for proper pH balance," according to Feline-Nutrition.org. While humans and other animals can get protein from grain and vegetables sources, cats can't process these same sources well. As a result, they must get it from other animals.
Fats are critical for the proper digestion, storage, and utilization of nutrients that power every part of the body. Essential fatty acids (meaning they cannot be produced in the body and must be obtained through food) are especially important. Though humans and other animals can get these acids from multiple sources, cats can't convert as much as they need from plant material. They must eat animals which have already converted this chemical for them.
Water is a vital component for all living things. However, cats evolved in desert climates, so they don't tend to drink as much water as other animals. While you should always make sure your cat has access to as much clean, fresh drinking water as it wants, be aware that cats in the wild get most of their water through moist animal meat.
What About Carbohydrates?
Simply put, cats have no dietary need for carbohydrates. They evolved to rely on fat and protein for energy. Their bodies are not very good at processing carbs, which is why cats fed a strict diet of grain-heavy dry food can be prone to obesity.
This doesn't mean you have to ban kibble completely. Many cats like the crunch of dry food, and your cat might be resistant to change if you try to take away her dry food she's eaten since she was a kitten. Try increasing wet food intake while decreasing access to dry food, or restrict kibble to treats to satisfy kitty's desire for crunchiness.