#031. Resolving My Beef with Kitty Carbohydrates

Quest to Find the Ultimate Healthy x Convenient Cat Food Solution (Part 1)

Note: I am taking a detour to talk about cat food - the most recent thing I am investigating through my lens of health and vitality. Enjoy!

This is Hamilton - Our 2 year old American Shorthair. He is a very picky eater. To my dismay, he loves kibble and is very particular about wet food. He will not eat wet food that is cold or has been refridgerated.

I love my cats, Hamilton and Maeve. I want them to live happily and healthily forever. This has led me to become very interested in cat nutrition.

Initially, when I found out that cats are obligate carnivores, I wanted to put ours on the BARF diet (Biologically Appropriate Raw Food) - a hilariously named low-carb cat diet that is comparable to a prey-based diet.

However, because we live active urban lifestyles, my partner wanted us to consider the convenience of a commercial pet foods. This was a reasonable request.

But immediately, the highly divergent part of my brain jumped to this being the kitty equivalent of oppression and industrialized diets as a cause of increased obesity and diabetes, like in post-colonial Native American populations. Yup, went there.

So an uproar ensued over what the cats should eat.

Our domestic drama aside, what I really wanted to know was, "What is the precise nutrient profile of what cats should eat, how much carbohydrate is allowable for optimum health, and how has that changed with domestication?"

Excellent question to geek out on and see if my philosophy on health holds up!

The Effects of Domestication

Well, one argument is that the domestication process has evolved the dietary needs of our pets. For instance, as the result of over 11,000 years of living with people, dogs fare much better eating starches (aka human food scraps) than wolves, five times better to be exact. This is because dogs have evolved more active genes to make amylase, an enzyme that breaks down starches.

To a degree, these effects of domestication are also seen in our pet cats, but are relatively modest compared to dogs because of the shorter history of cat domestication. Further complicating studies is the question of whether or not cats are truly domesticated. After all, some of our cat companions go out to mingle with the neighborhood feral cat population without human chaperones to control their feeding or breeding. Hm.

Adopt vs. shop debate aside, we know that Hamilton and Maeve are purebred American Shorthairs with a known breeding history of at least 5 generations back. The American Shorthair breed itself has been around since the 20th century. So, I think it’s safe to say that Hamilton and Maeve are thoroughly domesticated.

This is Maeve - Our 9 month old American Shorthair. She is a greedy eater. She will eat anything she is allowed to eat, including your finger if it smells like cat food. She will also eat anything Hamilton doesn't finish or is still trying to finish. Here she is on a scale at the Vet’s because we thought she may have worms, but nope, just fats. 

What the Research Says on Cat Carbs

Although domestication meant that it was probably okay for Hamilton and Maeve to have some carbohydrates in their diet, the question remained of “how much?”

Well, I found this doozy of a literature review that let me geek out on the "digestive physiology and metabolism of cats as it relates to the digestion, absorption and metabolism of carbohydrates, food selection and macronutrient balancing in healthy, obese and diabetic cats".

It dispelled some cats and carbohydrate myths, but also validated some of my concerns. Here are my takeaways (TLDR below):

1. Obesity is the main risk factor in the development of diabetes, not carbohydrate intake: A normal weight cat having a higher proportion of carbohydrates in their diet does not have an increased risk for diabetes (but does have risk for protein deficiency). On the other hand, “Each extra kilogram in body weight led to a 30% reduction in insulin sensitivity and glucose effectiveness and weight loss normalised insulin sensitivity.”

2. Carbohydrates get all of the bad reputation: It’s not just carbohydrates, it’s too much of any macronutrient (including protein and fat) that increases obesity risk.

3. Extra carbs don’t all turn to fat: Unlike humans, there is a relatively low conversion of excess carbohydrates to body fat. But excess fats are stored as body fat very efficiently.

4. Cats have a carbohydrate ceiling: Once a cat reaches about 300kJ of carbohydrates per day, they will be too “full” to eat more. In humans, we call these “empty calories” - high calorie, low nutritient foods. If they are full before their target protein intake, this can predispose a cat to protein deficiency. Note: 300kJ is a lot, for reference Hamilton and Maeve have a daily recommended calorie intake of 230kJ/day.

5. Cats aim for a high protein diet: Given the choice, domestic cats (in an experimental setting) would choose a macronutrient profile similar to that of a free-roaming feral cat, NFE 52%(ME) Crude Protein.

6. Commerical diets contain a high carbohydrate profile: Many traditional commercial diets contain more carbohydrates (up to 50% ME) than a feral cat would consume (2% ME) or domestic cats prefer when able to choose (11-21% ME).

7. Cats cannot taste sweet: They do not prefer carbohydrates, no after-dinner dessert needed. Note: This busted the myth that normal weight cats would get “addicted” to carbs. Greedy behaviors are more likely related to tasty food additives, that they are trying to reach their target protein levels, or a high prey-drive in juvenile cats.

8. Cats don’t digest starches very well: Cats have limited enzymes to digest starches, so once the starches reach the bacteria in the colon, there is more microbial fermentation. This can result in more adverse digestive effects such as diarrhea, flatulence, bloating.

9. Feeding should be individuated: The macronutrient proportions, total calorie count, and feeding strategies should account for individual factors such as spay/neuter status, age, activity levels, breed, history of domestication.

TLDR on Cats and Carbs

Initially, my war with cat carbohydrates was over concerns of cat diabetes. But it seems the real enemy is excess calories and obesity.

When given the choice, cats seem to natrually choose low-carb diets by proriotizing high protein. However, commercial foods have a higher carbohydrate content as a result of food processing methods. If this food is their only choice, cats will eat ingest as much as they need until they meet their target protein levels; but if they reach their carbohydrate ceiling first, they will be prone to protein deficiency.

So, the main reason to have a low-carbohydrate diet is not actually to prevent diabetes or weight gain, but to ensure a balanced diet with sufficient protein and the benefits that confers. Plus, the added bonus to you of less poop mass, less smelly poop, and less poop residue due to better cat gut health.

Final Words

Anyhoo, if it were still up to me, I would still give Hamilton and Maeve the BARF diet. But, now I’m comfortable meeting in the middle with a combination of high quality kibble and wet food.

Now that I know there is a window of tolerance for carbohydrates (one that could possibly be larger in domesticated breeds versus feral cats), I hope we can have our modern conveniences and healthy cats too.

Had you had a similar cat parent struggle? Tell me, I’m curious to hear!

Wondering what we feed our cats? Stick around, I’ll break that down in the next article!