Cats are obligate carnivores. That single fact decides almost everything about how you feed them. They cannot synthesize certain amino acids, fatty acids, and vitamins that other animals make for themselves, which means those nutrients have to come pre-formed from animal tissue. A diet that works for a dog or a human will slowly damage a cat.
The good news is that any food labeled "complete and balanced" by AAFCO (in the US) or FEDIAF (in Europe) has already done the math for you. Your job is to pick a reputable brand, match it to your cat's life stage, feed the right amount, and keep water available. Everything else is detail.
What cats actually need
A cat's diet has to cover six things:
- Animal protein, at roughly 26–35% of the dry matter for adults, more for kittens. Plant protein doesn't substitute. Cats can't use it efficiently.
- Taurine, an amino acid found only in animal tissue. Deficiency causes blindness and heart failure.
- Arachidonic acid, a fatty acid cats can't make from plant oils.
- Vitamin A in its retinol form. Cats can't convert beta-carotene the way we can.
- Arginine, in every meal. Without it, ammonia builds up within hours.
- Water. Cats evolved from desert animals and have a weak thirst drive. See how much water cats need. It's the single most overlooked part of feline nutrition.
A commercial diet that meets AAFCO or FEDIAF standards covers all of this. Homemade and raw diets often don't, even when the recipe looks careful. If you go that route, work with a veterinary nutritionist. (I tried a homemade raw diet for a year. Spent more on supplements than on the meat. Switched back to commercial wet food and the cat's coat got better within a month. Lesson learned.)
Wet, dry, or both
Both formats can be complete and balanced. They differ in moisture, texture, calorie density, and cost. Wet food helps with hydration and weight control. Dry food is cheaper and easier to store. Most cats do well on a mix.
Read the longer comparison at wet vs dry cat food before committing to one. The short version: if you're only going to feed one, lean wet. If you want the convenience of dry, pair it with wet meals or a water fountain.
Feeding by life stage
A cat's nutritional needs shift more than people realize.
- Kittens (0–12 months). Growing fast. Need kitten formula. Higher protein, fat, and calcium than adult food. Feed multiple small meals a day.
- Adults (1–7 years). Maintenance diet. Two measured meals a day is the standard.
- Seniors (7+ years). Lower activity but often higher protein needs to preserve muscle. Watch for weight changes in either direction and adjust.
The full breakdown of meals per day, portion sizes, and free-feeding versus scheduled is in the cat feeding schedule guide.
What not to feed
Several common human foods are toxic to cats, some in tiny amounts. The list is short but non-negotiable: onions, garlic, chocolate, grapes, raisins, alcohol, xylitol, raw dough, and a handful of others. Lilies aren't food but cats chew them and they cause kidney failure. The full list, symptoms, and what to do is at foods toxic to cats. Read it once and screenshot it.
Also avoid: cow's milk (most cats are lactose intolerant), raw fish (thiaminase destroys vitamin B1), and dog food (no taurine).
The weight problem
Roughly 60% of pet cats in the developed world are overweight or obese. The most common nutrition-related health problem, and it shortens lives quietly. Diabetes, arthritis, fatty liver disease, urinary issues. If you can't feel your cat's ribs without pressing, they're probably carrying too much.
Weight loss in cats has to be slow and supervised. Rapid fasting causes fatal liver damage. The how-to is at overweight cat diet.
A practical starting point
If you're feeding a healthy adult cat and want a default:
- A complete-and-balanced wet food, twice daily, portioned by the label for your cat's target weight.
- A small measured amount of dry food if you want, not free-fed.
- Fresh water in two locations, away from the food bowl.
- A vet check once a year to weigh in and adjust.
That covers 95% of cats. The other 5% have a specific condition (kidney disease, diabetes, allergies) that needs a prescription diet. Your vet will tell you. Don't diagnose your cat from a forum.