Every grain-free cat food I've seen is filled with vegetables like sweet potatoes and peas. Why is this? Why don't they just put more meat? Are there 100% meat product cat foods, wet or dry?
Why are vegetables put into commercial cat food?
There's two reasons: cost and perceived health benefits.
First, plant proteins are cheaper than animal proteins. When the food costs less to produce, the profit margin can be higher for the company.
Second, people are accustomed to believing that vegetables are healthy (because for us, they are). Cats, on the other hand, cannot digest plants. Plants are not healthy for cats, they are filler. Since people buy the food, it's marketed to us and not to our cats directly.
Does any cat food contain 100% meat
Not quite. Cat food is required to contain a number of vitamins/minerals to make up for nutrients that are lost in the processing (cooking) of animal proteins.
In addition, dry foods cannot contain a large percentage of meat because they do not hold together into kibbles. Kibble is a cereal (I believe it's often spray-dried) and so requires some amount of plant material to act as glue. The highest meat content I've ever seen in a dry food is 87% (Evo Cat and Kitten).
Canned foods, on the other hand, can be almost entirely made of meat. I'm familiar with Evo's venison and duck varieties, which are 95% meat and are particularly good for cats with allergies since they have a very limited ingredient list (though my cat who has allergies doesn't like them and we have to put something else on top). There are several smaller companies that make 90%+ meat canned foods (I suspect the manufacturing is easier than high meat dry foods), I'm just not very familiar with them.
There are also smaller companies that make frozen 90%+ meat frozen foods. I'm able to find them in my local organic market's freezer section.
Cats need meat, not veggies! Manufactures are adding peas, carrots, and spinach to save them money. Granted it lowers the price to consumers, but at the cost of poorer health for their cat. The percentage of vegetable matter in what a wild feline ingests in their prey is far below what is in the manufactured product!
Why are grain-free cat foods filled with vegetables instead of more meat?
Because vegetables (and grains) are adequate sources of nutrition for your cat.
Why don't they just put more meat?
Adult cats only require their diets to be a minimum of 26% protein to maintain their weight and health (per the AAFCO - see page 13). A balanced diet for a healthy and thriving cat is relative to their health profile (weight, activity level, age, etc.) and not determined by what a cat might be able to survive on if it were in the wild. Cats need a balanced mix of digestible and absorbable protein, fats, vitamins and minerals. Carbohydrates, starches, fiber and sugars are not "essential" nutrition, however, the right kinds are beneficial.
Especially if you have an indoor cat, too much protein can mean a fat cat. If your cat has kidney problems, too much protein can also be harmful.
Can I feed my cat too much protein?
If your cat eats too much protein, some will be excreted in the urine and the rest will be used as calories or converted to fat - causing your cat no harm. However, if your cat has a kidney problem, high protein diets are not recommended. Most pet food companies slightly exceed the minimum recommended protein requirements to ensure that cats get adequate protein from their food.
Are there 100% meat product cat foods, wet or dry?
Feeding your cat 100% meat does NOT mean that your cat is also getting 100% protein.
Per the USDA:
The muscle is approximately 75% water (although different cuts may have more or less water) and 20% protein, with the remaining 5% representing a combination of fat, carbohydrate, and minerals.
If you feed your cat 100% meat then they will be getting an unbalanced and unhealthy diet. In particular they won't be getting enough of the essential vitamins they need to maintain a healthy weight and thrive.
My 3 cats have been fed the Raw Meat diet for 15 years. (You can look it up on line) Basically raw human grade chicken with supplements & some vitamins added, also an Organic raw egg added to the mix.
They are all healthy & have never been to a Vet, I also grow Organic grass if they want to nibble on it. Barley,oat & wheat grass seeds can be purchased on line. Never feed Kibble.It's the worst food for any animal. It can eventually lead to Kidney problems & diabetes in older cats. Also avoid dairy, contrary to what people think most cats are lactose intolerant They like it, but it's not good for them.( Dairy isn't good for anyone except BABY humans & Baby animals)
Cats are Obligate Carnivores they do NOT NEED Veggies,Fruit or Grain in their diet. When they eat prey they get a bit of what that animal ate,seeds or veg, matter but it's very little.Some cats may like a small bit of cooked veggie occasionally but they really can't digest it properly.
The above article explained it clearly.The only reason plant matter is added to cat food is for Profit! (Not for the animals benefit)