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What Happens When You Feed Your Cat Carbs

Big Pet Food would love nothing more than for you to feed your cat their ultraprocessed, carb-based foods. But is that in your pet's best interests? Can her body actually handle grains and starches? Find out what can happen when you follow their blind-sighted feeding recommendations.

cats and carbs


  • The ultraprocessed pet food industry is highly motivated to convince pet parents that cats aren’t carnivores and can thrive on carbohydrate-stuffed diets
  • The scientific fact that cats are indeed true carnivores, coupled with a nutritional awakening among cat parents poses a problem for an industry that has made its fortune selling biologically inappropriate grain- and carb-based cat food
  • The reality is that cats’ bodies aren’t designed to digest carbohydrates efficiently, and most carbs in a cat's diet convert to sugar and fat — leading to obesity and related diseases
  • Bottom line: Unprocessed animal tissue is an essential and species-perfect source of protein, vitamins, and moisture for cats; no adequate substitute exists
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A 2017 study with the eye-catching title "Cats and Carbohydrates: The Carnivore Fantasy?" is another unfortunate example of how corporate capture of what are presumed to be independent entities extends beyond another, more recent glaring example: Big Pharma’s capture of the U.S. FDA.

In the 2017 case, a pair of university veterinary researchers, one in Canada and the other in Belgium, co-authored a paper that purports to explore how cats digest carbohydrates. As a veterinarian, I was curious as to why veterinary researchers would be involved in a study that suggests cats aren’t really carnivores (when in fact, felines are obligate, hypercarnivores).

My question was answered when I reached the end of the report and read, under the Conflicts of Interest section, that one of the two researchers is the Royal Canin Veterinary Diets Endowed Chair in Canine and Feline Clinical Nutrition at the Ontario Veterinary College.

As many of you who read here regularly have learned, most veterinary colleges leave all their nutrition training and collaborative research in the hands of very large ultraprocessed pet food companies, in this case, Royal Canin (owned by candy bar giant, Mars, who also own Antech veterinary labs and thousands of VCA veterinary hospitals).

Big Pet Food Wants You to Believe Cats Aren’t Carnivores

In recent years, dog parents have become increasingly interested in ensuring they’re feeding their pets species-specific diets, and the pet food industry has responded by trying to convince the world dogs can be vegans and should be eating diets high in grains and starches.

Felines present an even greater problem for Big Pet Food, because as true carnivores, they have even less ability than dogs to benefit in any way from eating refined carbs (and, like dogs, they have no nutritional requirement for them), and pet parents are catching on.

How is the ultraprocessed pet food industry supposed to continue to sell massive amounts of biologically inappropriate grain and starch-based diets to cat owners who are increasingly demanding diets designed for their strict meat-eating feline family members?

Apparently, one way is to push the idea that it’s a "fantasy" that cats require meat-based vs. plant-based diets, and then conduct studies with a predetermined outcome to offer as evidence.

The Focus Is on Ingredients Cats Don’t Need

Here’s an example of the "science" behind ultraprocessed cat food. This is from, referencing the "carnivore fantasy" study:

"Once cats do manage to digest carbohydrates, they can’t use the end products, such as glucose, as well as dogs do. Scientists found that uptake of the simple sugar, or monosaccharide, glucose took twice as long in cats as in dogs. Cats also seem to lack the ability to alter their uptake of digested carbs based on the quantity in their diet, which dogs are able to do.
However, the authors of the literature review noted that research is inconclusive on what concentration of sugars is needed to reach maximum uptake in cats’ intestines.
That means scientists don’t know if the carb concentration in cat food is beyond or below what cats’ digestive systems can use. One early study, from 1977, did find that cats could digest 40 to 100 percent of the starch in cat foods, depending on the carbohydrate source."

This is a stunning example of just how focused processed pet food producers are on learning how much dogs and cats can tolerate of the biologically inappropriate ingredients in their formulas. These statements also highlight how these foods contribute to the incidence of diet-induced diabetes in pets consuming large amounts of unnecessary starch (sugar).

Anyone interested in the long-term health, longevity, and vitality of dogs and cats should be focused on offering the full range of dietary nutrients their bodies are designed to make the best use of — not how many different inappropriate ingredients they can tolerate, and in what quantities.

Carbs Can Cause Enormous Damage to Your Cat’s Health

Felines aren’t designed by nature to digest large amounts of carbohydrates. And since domestic cats evolved to eat very low amounts of grains and starches, simple common sense tells us that a diet high in carbohydrates has the potential to create ill health (example: the feline obesity and diabetes epidemics that can be reversed by eliminating starch from the diet).

The activity of a cat's liver enzymes is designed to handle protein and fat as energy sources, not starches. Most of the carbs in a cat's diet are ultimately stored as fat. Macronutrient self-selection research shows cats choose diets with less than 12% carbs; higher levels require the pancreas to produce more insulin and digestive enzymes to break them down.

Many cats end up with chronic pancreatitis, inflammatory bowel disease (IBD) and diabetes as a result of chronic dietary abuse from excessive starch they cannot metabolically manage.

Not surprisingly, you won’t find carbohydrate content listed on your bag of cat food because manufacturers keep it under wraps. Do this simple equation to find out how much sugar you’re feeding: add up the amount of protein, fat, moisture, and ash (estimate 6% if it’s not listed) and subtract from 100. That number is the percentage of carbs (sugar) found in your kitty’s food.

It’s easy to see why so many cats have chronic inflammatory and degenerative diseases — they’re being fed a very unnatural diet of refined carbs their bodies aren’t designed for.

Research shows that cats fed diets high in simple sugars become hyperglycemic (the first symptom of insulin resistance). Most cats aren't attracted to sweet-tasting foods (unlike dogs and people), and instead prefer food that tastes like animal products. This is one of several clear indicators of the strict carnivorous nature of felines.

Unprocessed Animal Tissue Is Perfect Nutrition for Cats

Felines have a unique nutritional biochemistry that is significantly different from other animals. As obligate carnivores, they must consume animal tissue to meet their very specific nutritional requirements.

For example, kittens require 1.5 times the amount of protein as the young of other species, and adult cats need 2 to 3 times the amount other adult animals require. This is because omnivores and other mammals use most of the protein they consume not as a source of energy, but for growth and body maintenance.

Cats use protein for those purposes plus as a source of energy. When most animals are fed a low-protein diet, their bodies conserve amino acids to manage the deficit. But a cat's body must continue to use protein even when there's not enough in the diet, which is why protein malnutrition happens quickly in sick or injured cats, and those with anorexia.

In addition to their increased need for meat-based protein, cats also have a higher requirement for certain specific amino acids, such as taurine, found naturally in animal tissue. They also have a special requirement for vitamin A, which is available naturally only in animal tissue.

They lack the intestinal enzymes necessary to convert B-carotene in plants to the active form of vitamin A. Vitamin A is essential for maintenance of vision, growth of bone and muscle, reproduction, and the health of epithelial tissues.

Vitamin D is also essential in the diets of cats because they lack the ability to synthesize it through their skin. The liver and fatty tissue of free-range animals is rich in vitamin D.

Domestic cats evolved from desert-dwelling ancestors, which is why they must get most of their water from the food they eat. Felines are not as responsive as other animals to sensations of thirst or dehydration.

When fed a dry food diet, cats aren't driven to search for another source of water to make up the difference between what their bodies require and what their diet provides. This results in chronic mild dehydration, a condition that will ultimately lead to disease, especially of the lower urinary tract and kidneys.

Cats and Carbohydrates: The Big Pet Food Fantasy

As always, it’s "buyer beware" when selecting commercially available cat foods. As hard as certain activist organizations and the pet food industry may try to convince you otherwise, dogs will remain scavenging carnivores and cats will remain obligate carnivores, and neither will evolve to require highly refined, carbohydrate-laden diets.

Feed your cat a healthy variety of biologically appropriate foods by offering a combination of homemade raw (or gently cooked), commercially available balanced raw, dehydrated/freeze dried raw, and/or human grade canned. The diet you feed your feline family member should be nutritionally optimal, species-specific, and made from high-quality meat protein sources. You can find a few homemade recipes to try here.