Quick answer
Cats are obligate carnivores: they need animal protein and fat, plus essential nutrients such as taurine, from a complete cat food. Wet food helps hydration and kidney support; measured meals beat free-feeding dry kibble for most indoor pets.
Obligate carnivore basics
“Obligate carnivore” means cats are biologically dependent on nutrients found in animal tissue. Unlike dogs (facultative carnivores / omnivore-leaning scavengers in practice), cats have limited ability to synthesise certain amino acids, fatty acids, and vitamins from plant precursors.
In the wild, small prey (rodents, birds, insects) delivered a high-protein, moderate-fat, low-carbohydrate package with natural moisture. Pet cats still carry that metabolism. A bowl of complete commercial cat food is the modern stand-in — not a plate of vegetables, not dog food, and not an unbalanced scrap diet.
International Cat Care and AAFP nutrition guidance both emphasise complete, balanced diets appropriate to life stage. Treats should stay a small fraction of daily calories so the main ration still meets nutrient targets.
Key takeaway
Feed a complete cat food built for carnivores — not vegetarian diets, not dog food, and not random human leftovers as the main meal.
Taurine and other key nutrients
Taurine is the headline nutrient owners hear about — and for good reason. Cats have a high dietary taurine requirement; deficiency historically caused dilated cardiomyopathy, retinal degeneration, and reproductive failure. Reputable complete cat foods are fortified to prevent that. Homemade or poorly stored diets are where taurine gaps still appear.
Cats also need preformed vitamin A (they convert beta-carotene poorly), arachidonic acid, adequate arginine, and enough high-quality animal protein to maintain muscle. Carbohydrate is not a required macronutrient the way it is for some omnivores, though many commercial foods include some starch for processing and energy.
Merck Veterinary Manual nutrition chapters and veterinary nutritionists caution against boutique raw or home-cooked plans without laboratory formulation. Pathogens (Salmonella, Listeria) and calcium/phosphorus imbalances are real risks — especially for kittens and immunocompromised households.
Wet food benefits for kidneys and hydration
Cats have a low thirst drive relative to dogs; they evolved to obtain much of their water from prey. Dry kibble is typically ~6–10% moisture; canned food is often ~70–80%. That difference matters for urinary tract health and for cats heading toward chronic kidney disease (CKD) — extremely common in older cats.
| Food type | Role | Notes |
|---|---|---|
| Complete wet (canned / pouches) | Strong default | High moisture supports urinary and kidney health |
| Complete dry (kibble) | Convenient | Easy to overfeed; always provide fresh water |
| Mixed wet + dry | Common compromise | Count total calories; do not double-portion |
| Raw / homemade | Only with vet nutrition plan | Pathogen and imbalance risks without formulation |
Many clinicians recommend including wet food daily, plus water fountains for cats that prefer moving water. Longevity and kidney monitoring are covered in how long do cats live? .
Portions and free-feeding risks
Leaving a bottomless bowl of dry food seems kind; for many indoor cats it is a fast track to obesity, diabetes, and arthritis. Neutered adults with low activity often need fewer calories than package “average” guides suggest.
Better defaults: weigh food, split into scheduled meals, and use puzzle feeders so hunting behaviour burns mental energy. Reassess body condition monthly — you should feel ribs under a light fat cover and see a waist from above.
Key takeaway
Measured meals (with moisture) beat all-day dry free-feeding for most pet cats — especially indoor adults.
Kitten, adult, and senior feeding
| Life stage | Diet focus | Notes |
|---|---|---|
| Kitten (growth) | Kitten-formulated food | Higher calories, protein, and DHA; free-choice only if weight stays on track |
| Adult (maintenance) | Complete adult cat food | Measured meals; wet food helps water intake |
| Senior / CKD risk | Vet-guided diet | Often higher moisture; prescription renal diets when diagnosed |
| Indoor / low activity | Calorie-controlled | Obesity common with free-fed dry food |
Transition between formulas over 7–10 days to reduce digestive upset. Senior cats with rising thirst, weight loss, or picky eating need veterinary bloodwork — diet alone cannot diagnose CKD or hyperthyroidism.
Toxic foods and plants
Keep cats away from onions, garlic, chives, grapes and raisins, xylitol (in some sugar-free products), alcohol, caffeine, chocolate, and raw yeast dough. Bones can fracture teeth or obstruct. Milk is unnecessary and often causes diarrhoea in adult cats.
True lilies (Lilium and Hemerocallis species) are a feline emergency: pollen, petals, leaves, and even vase water can trigger acute kidney failure. ASPCA poison-control plant lists are a reliable home-check resource. Full clinical detail: lily poisoning in cats .
Feeding basics: step-by-step
- Choose a complete life-stage food. Pick a reputable kitten, adult, or senior formula that meets recognised complete-and-balanced standards. Avoid unbalanced homemade diets unless a veterinary nutritionist designs them.
- Prioritise moisture. Offer wet food daily when possible, plus fresh water bowls or a fountain. Extra water supports kidneys and the urinary tract.
- Measure portions — do not free-feed by default. Weigh or scoop meals. Free-choice dry food is a common path to obesity in indoor cats.
- Feed on a predictable schedule. Two to four small meals often suit adult cats better than one large dump. Use puzzle feeders to slow eating.
- Keep toxins and unsafe foods out of reach. Never offer toxic human foods. Remove true lilies from the home — they can cause fatal kidney failure in cats.
- Recheck weight and labs with your vet. Adjust calories as activity changes. Middle-aged and senior cats benefit from kidney and dental monitoring.
Broader care: how to care for a cat · indoor vs outdoor lifespan .
Sources
FAQs
What do cats eat?
Cats are obligate carnivores. They need a complete diet based on animal protein and fat, including essential nutrients such as taurine. Quality commercial wet and/or dry cat foods formulated for their life stage are the safest everyday choice.
Why must cats eat meat?
Cats cannot thrive on vegetarian or vegan diets. Their metabolism requires nutrients abundant in animal tissue — notably taurine, arachidonic acid, and preformed vitamin A — that plants do not supply in usable amounts.
Is wet food better than dry food for cats?
Wet food’s high moisture content helps many cats stay hydrated and may support urinary and kidney health. Dry food is fine as part of a complete plan if portions are measured and water intake is good. Many vets prefer at least some wet food daily.
Can cats free-feed dry food all day?
Free-feeding often leads to obesity, especially in indoor cats. Measured meals or puzzle feeders are safer. Ask your vet for a target weight and daily calorie range.
What human foods are toxic to cats?
Keep cats away from onions, garlic, grapes/raisins, xylitol, alcohol, caffeine, raw bread dough, and especially true lilies (including pollen and water). Chocolate is also unsafe. See our lily poisoning guide for plant emergencies.
Do kittens, adults, and seniors eat the same food?
No. Kittens need growth formulas; adults need maintenance calories; seniors often need easier chewing, joint support, and sometimes prescription diets for kidney disease. Transition foods gradually.
How much should I feed my cat?
Follow the feeding guide on a complete food as a starting point, then adjust to keep a visible waist and palpable ribs under a slight fat cover. Individual needs vary with age, neuter status, and activity.
Related: Cat profile · Foods dogs cannot eat · Pet health hub