Why cats need meat, not marketing (and why most supermarket cat food fails them)

A cat is not a small dog. A cat is a small lion. The biology behind this is unforgiving and it is the reason most supermarket cat food fails them.

This piece is for owners who pick up a Whiskas pouch, a Friskies bag, or a Felix sachet and assume "cat food is cat food, my cat eats it, therefore it is fine". I want to explain, with the actual physiology, why this assumption costs cats years of healthy life.

The obligate carnivore problem

Cats are classified as obligate carnivores. The word "obligate" matters. Dogs are facultative carnivores, meaning they can survive on a varied diet including grains and vegetables if necessary. Cats cannot. Their digestive system, liver enzymes, kidneys, and amino acid metabolism evolved over millions of years on a near-100-percent meat diet, mostly small rodents and birds caught fresh.

Three things cats cannot do:

1. Synthesise taurine. Taurine is an essential amino acid for cardiac muscle, retinal function, bile salt formation, and reproduction. Dogs make their own from cysteine and methionine. Cats lack the enzyme. Without dietary taurine, cats develop dilated cardiomyopathy (a heart condition that kills them in months) and central retinal degeneration (irreversible blindness). Every quality cat food adds taurine on top of the natural taurine found in animal tissue.

2. Convert beta-carotene to vitamin A. Dogs and humans take plant beta-carotene and convert it. Cats cannot. They need preformed vitamin A from animal liver. Vegetarian cat food is biologically impossible without synthetic supplementation, and even then it is risky.

3. Synthesise arachidonic acid. This omega-6 fatty acid is essential for inflammatory regulation, kidney function, and reproductive cycling. Cats need it preformed from animal fat. Plant fat alone (linoleic acid) is not enough.

There are more (vitamin D from animal sources, niacin, certain B vitamins, glycine for bile) but these three explain why "cat food" cannot legally be plant-based and stay healthy.

What this means for the protein number

A healthy adult cat needs at least 32 percent crude protein, ideally over 35, from animal sources. Compare that to dogs (25 percent for adults). The difference is not preference, it is physiology. Cat livers are calibrated to constantly metabolise high protein. If a cat does not get enough dietary protein, the liver does not slow down, it starts breaking down the cat's own muscle to make up the difference. Sustained low protein in cat diets causes muscle wasting visible within months in older cats.

Most cheap supermarket cat kibble is formulated to 30-32 percent crude protein (the minimum) using a combination of cheap meat by-products and high cereal content. Mathematically the protein percentage is met. Biologically, the protein quality (digestibility, amino acid profile) is not. Cats fed this kind of food often look thin even when their weight is normal because they are losing muscle mass and replacing it with abdominal fat.

A premium cat food (Acana, Wellness CORE, Orijen Cat) typically lands at 35 to 40 percent crude protein with named fresh meat as the first three ingredients and zero plant-protein concentrate.

The water problem

Cats are descended from desert ancestors. Their thirst drive is weaker than dogs. In the wild, a cat gets most of its water from prey, which is 70 to 80 percent moisture. Modern dry kibble is 8 to 10 percent moisture. A cat fed only dry kibble drinks the difference voluntarily. Most do not drink enough.

The consequences are:

Chronic kidney disease (CKD). The most common cause of death in cats over 10. Strongly correlated with dry-only diet.
Lower urinary tract disease including struvite and oxalate crystals, blockages in male cats which are surgical emergencies.
Constipation in older cats.

The fix is wet food. Even partial. Best practice in 2026 vet recommendations: feed mostly wet food with kibble as a topping, or alternate wet and kibble meals. Pure-kibble diets are no longer considered best practice for indoor cats with limited activity.

Why the supermarket pouches still fail

You might think: "OK so I will switch to wet food. Whiskas pouches are wet, problem solved."

Not really. Here is the catch.

A typical supermarket wet pouch (Whiskas, Friskies, Felix, Gourmet, Sheba) advertises one of these:

"Beef" — actually 4 percent beef
"Chicken" — actually 4 percent chicken
"Salmon" — actually 4 percent salmon

The other 96 percent is water (correct for hydration) plus unidentified animal by-products plus added sugar plus colourants plus flavour enhancers. The protein count comes out around 8 to 12 percent crude (which equals roughly 40 percent on a dry matter basis once you remove water — close to the kibble equivalent).

So you are getting the moisture benefit. Good. But the protein quality is identical to the cheap kibble: vague by-products, single trace amount of advertised meat, sugar to mask the rest.

A premium wet food (Tiki Cat, Applaws Natural, Schesir, Lily's Kitchen, Almo Nature) advertises 70 to 75 percent visible meat (actual chunks of identifiable fish or chicken in a clear broth) and contains zero added sugar. The protein count on the analysis is similar to the supermarket pouch on a dry matter basis, but the digestibility and the amino acid profile are far higher.

What an actually good cat food day looks like

Based on current vet recommendations and our PetFoodRate methodology, a healthy 4 kg adult indoor cat should eat approximately:

180 to 220 g of wet food per day (premium grade, 70 percent meat, no added sugars), split into 2 to 4 meals
Or if you mix, 100 g wet + 30 g premium kibble
Fresh water always available, ideally in a wide low bowl placed away from the food (cats hate when food smells contaminate water)
Zero treats with sugar or "tasty bits" colorants
Optional: a small amount of plain cooked chicken or fish (no salt, no spices) once a week as variety

The cost: roughly 1.50 to 2.50 EUR per day for a quality wet diet, which is more expensive than supermarket pouches (around 0.80 EUR per day) but cheaper than the medium-term vet bills for CKD treatment, urinary blockages, dental cleanings, and diabetes management.

How to switch without a fight

Cats are notoriously stubborn about food changes. The transition rules:

Week 1: keep the old food, add a tiny portion of new food on the side. Most cats sniff it and ignore. That is fine. Week 2: replace 25 percent of the old with new, mixed in the same bowl. Week 3: 50/50. Week 4: 75 percent new, 25 percent old. Week 5: 100 percent new.

If your cat outright refuses the new food at any stage, slow down. Never starve a cat to force compliance. Cats cannot fast for more than 48 hours without risking hepatic lipidosis (fatty liver), a serious metabolic emergency. If the transition fails entirely, try a different brand of premium food or a different protein source. Some cats imprint on textures (pâté vs chunks vs gravy) more than flavours.

Bottom line

Your cat is not a picky eater because it is spoiled. It is a picky eater because its body knows what real food smells like. The supermarket pouch industry built its empire on disguising vegetable matter and water with sugar and meat flavouring. It works on humans (we buy it) and on cats (they eat it). It does not work on cat physiology, which is why the average lifespan of a kibble-only cat is several years shorter than that of a cat on premium wet food and good vet care.

PetFoodRate exists to make it easy to find the brands that do this right. Our top-graded cat foods are at /best/wet-cat/ and /best/kibble-cat/. The bottom-graded ones are not hidden either. The methodology is at /methodology.

Your cat cannot read the label. You can.

— Sophie Lefevre, Species Nutrition Specialist, PetFoodRate