Updated August 2023

Cats are obligate carnivores. They require a meat-based diet for optimal health. Their natural diet is prey, such as rodents, rabbits, lizards, insects, and birds. These prey consist primarily of water, protein and fat. Less than 10% of a prey animal is carbohydrate (most as stored glycogen in liver and muscles).

Cats use protein and fat for energy. They lack the metabolic pathway that humans and dogs use for processing carbohydrates. While cats can digest and use carbs, cats, any excess gets turned into fat. Nearly 60% of U.S. cats are now overweight or obese.

Veterinarians know this. They also know that the rate of obesity has risen every year since tracking began in 2010. The most common cat food—dry kibble—clearly isn’t doing cats any favors! Yet veterinarians rarely counsel clients about nutrition because they didn’t learn about it in vet school. Thanks to pet food company marketing, most vets still recommend dry foods.

Diseases associated with obesity have also increased. The rate of feline diabetes doubled from 1 in 400 to 1 in 200 in a decade. Yet Type 2 diabetes (the most common in cats) is not only preventable but completely reversible with diet.

We need to take a completely different approach to feline nutrition!

Dry Foods Aren’t Good for Cats

Dry foods contain 30-40% carbohydrate (or more!) as starch and fiber. “Grain-free” foods contain as much carbohydrate, but in the form of starchy vegetables.

Some starch is necessary for the machinery that makes kibble. Grains and starchy vegetables also provide cheap calories. Dry food has a much higher profit margin than any other form. This benefits both manufacturers and veterinary clinics, so they push it—hard.

Adult cats need 2-3 times more protein than dogs. Yet dry cat foods only contain about 1/3 more protein than dry dog foods! Diets for cats with kidney disease are even more restrictive. Protein is the most expensive ingredient, so manufacturers prefer to use less of it, padding the food with carbs instead.

Dry food ingredients go through four high-heat processes. This denatures (damages, distorts) proteins in the food. Such unnatural proteins can lead to food allergies, inflammatory bowel disease, or even cancer.

A prominent feature of the cat’s natural diet is its high water content. Prey animals like rodents, rabbits, and birds contain 65-70% water. (Insects are a little drier, at about 50%.) Dry foods contain only 10% water. They are completely unnatural for a cat.

Our feline friends descend from desert-dwelling wild cats who have limited water resources. Their ultra-efficient kidneys satisfy their moisture needs from their prey. Cats have a very low thirst drive and will not drink water until they are up to 3% dehydrated. A veterinarian should consider IV fluid therapy at that level! Cats eating only dry food take in half the moisture compared to a cat eating only wet food. Chronic dehydration contributes to bladder inflammation, crystals, stones, and kidney failure.

Cats prefer food that has a strong meat or fat flavor. Pet food manufacturers go to great lengths to make dry food palatable to cats. They coat the kibbles with fat and palatability enhancers. The result may be a cat who overeats not because he’s hungry, but because he loves the food too much! (I do the same with Fritos!)

Wet Foods Are the Best Choice

The most logical strategy is to feed cats a diet that mimics the natural prey diet, which is 50 to 70% moisture. Nutrients come out to about 55% protein, 35% fat, and 10% carbohydrate.

Raw, frozen, and reconstituted freeze-dried foods also work very well. But many people can’t do homemade, and commercial raw products can be expensive.

Feeding more (or only) canned food is a good approach. It’s often easier for people to deal with. Canned cat foods contain about 45-50% protein and 8-10% carbohydrate. Canned kitten foods may contain up to 55% protein, with high moisture and low carbs. The moisture keeps a cat’s fluid intake high. Ingredients are better digested and utilized. Cans are recyclable, which is not the case for foods in plastic pouches or similar packaging.

Bonus: Wet foods produce much less solid waste in the litterbox!

The Importance of Variety

Another feature of the cat’s natural diet is diversity. A hunting cat doesn’t eat only purple finches! He will eat any small prey he can catch, whether it be mice, voles, pigeons, grasshoppers, or geckos. Likewise, we should feed our cats a variety of foods.

Canned cat foods come in a wide assortment of brands, flavors, forms, and special ingredients like cheese or blueberries. Once your cat accepts canned food, it’s easy to vary her meals. Raw and homemade foods are also easier to alter frequently than kibble. My cats don’t get the same food twice in a row!

Feeding different brands and flavors reduces the chance of dietary excess or deficiency of any single nutrient. Ingredient suppliers and manufacturers make mistakes. Foods with too little thiamine or too much vitamin D end up on store shelves. They get recalled—but not before they sicken or kill pets.

Variety keeps cats from becoming finicky and food addicted. It prevents food intolerances, allergies, and inflammatory bowel disease. Feeding the same dry kibble day in and day out, year after year, increases the risk of these problems. Cats get bored with the same food all the time—wouldn’t you? With canned food, it’s easy to vary brands, flavors, and protein sources.

Preventing and Solving Weight Problems

Multiple factors cause obesity. But free choice, 24/7 availability of dry food is a major player. Fat, “chonky” cats are not cute, they’re unhealthy. They’re prone to arthritis, liver and kidney disease, skin problems, gastrointestinal issues, heart disease, and diabetes. It’s riskier to put them under anesthesia. They have a shorter life expectancy.

Overweight cats need low-carbohydrate diets (think keto or Atkins). Experts now recommend canned food as the primary treatment for diabetes. A high-protein, high-moisture diet can reverse diabetes in many cats! Wet diets can even prevent this devastating disease.

Overweight cats should be eating an all-wet diet. Stick to foods containing 10% or less carbohydrate. Many “all life stages” and most kitten foods work very well. Many foods now list their carbohydrate content (this will be required in the next few years). If not, just subtract all the listed ingredient percentages from 100. This gives you a ballpark estimate of carbs. It should be 10% or less. Cats lose more weight on canned food than dry food diet: they lose body fat while retaining lean muscle mass. These diets are much better suited to the unique feline metabolism. Occasionally, an obese cat will temporarily gain weight on canned food. If that happens, don’t panic! As her metabolism adjusts, the weight will come off.

How to Switch Foods

If your cat is not used to eating canned food, add it to the diet in small amounts. It is so different in composition from dry food that it may cause tummy upset at first. (Adding digestive enzymes and probiotics can help with this.) If a cat won’t eat canned food, he may be a dry food addict, or not hungry enough to try something new. Try feeding in timed meals. Leave dry food out for only an hour, two or three times a day. Once he’s accustomed to the schedule, give a little canned food first. Most cats will try it at that point. (See “Switching Foods” for tips on why and how to make the change.)

Quality is as important with canned cat food as any other type of food. See this article to learn how to read a label and assess a food’s quality for yourself.

Dry food is a great convenience. But at least 75% of the diet (100% if you want to ensure optimal health!) should be canned, raw, or homemade food. Yes, you’ll spend a little more on food up front. But you’ll save hundreds, if not thousands, on veterinary bills for preventable, diet-related diseases.

Dr. Jean’s  best-selling ebook What Cats Should Eat It contains her personal recommendations for the best brands and flavors of food based on the latest science! It’s available at Amazon.com. (You can read it on a smartphone, tablet, PC or Mac, no Kindle required!)

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