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25 Apr 2025

Carbohydrates for cats: energy alternative or silent enemy?

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Carbohydrates for cats: energy alternative or silent enemy?

» Introduction

Cats (Felis silvestris) are one of the oldest domestic animals in the world, having accompanied humans for more than 10,000 years.

The ancestors of cats originated in Africa and were introduced to Europe and Asia during the Neolithic era, about 11,000 years ago, undergoing a long process of evolution and gradually differentiating into different subspecies and breeds (Xuan et al., 2023).

Genetic analyses have shown that all domestic cats, including both purebred animals and those that roam freely, descend from the subspecies Felis silvestris libyca, the wildcat of North Africa (Serpell, 2013, Xuan et al., 2023).

Its domestication likely occurred somewhere in Western Asia (Serpell, 2013), a region currently occupied by Egypt, Israel, Palestinian Territories, Lebanon, Syria, Iraq, Turkey, and Iran, around 4,000 years ago (Duperré, 2019).

It is believed that this was a relatively slow and natural process that began alongside the development of agricultural practices in the Middle East (Bradshaw, 2013), a situation that attracted a large number of rodents and pests to human settlements, resulting in an accumulation of organic waste.

In this way, the wildcats were attracted to inhabited areas in search of food, following a commensal path towards domestication (Hu et al., 2014; Xuan et al., 2023).

In this context, genetic studies have revealed that wildcats may have consumed grains and cereal by-products, as well as waste and leftovers from human food, suggesting that this species rummaged among people or was fed by them. Gradually, it adapted to their lifestyle while also fulfilling roles in protecting crops and human property.

These processes would have led to the role of cats as predators of rodents and small animals in settled communities, their adoption as pets, and the expansion of cat populations worldwide, a process facilitated by human mobility (Hu et al., 2014; Xuan, 2023).

Over time, variations in the genome of wildcats resulted in changes in their morphology, social behavior, and feeding habits, making them more docile, closer to humans, and capable of accepting variations in their diet, gradually evolving into the modern cats known today (Xuan, 2023).

The cat: strict carnivore

Due to the genetic legacy of their wild ancestors, who based their diet exclusively on hunting, the domestic cat is classified from a dietary perspective as a strict carnivore, meaning that, in their natural habitat, they are adapted to the consumption of small prey, such as rodents and birds, throughout much of the day and night.

From a nutritional perspective, this diet, strictly composed of animal tissues, is rich in proteins, moderate in fats, and includes only minimal amounts of carbohydrates (52%, 46%, and 2%, respectively) (Fascetti, 2013; Verbrugghe and Hesta, 2017).

Over time, the consumption of this type of diet has generated specific requirements, as well as unique adaptive changes in the digestion and carbohydrate metabolism of this animal species.

In fact, this process has been the basis of claims traditionally surrounding cat nutrition, such as their inability to efficiently utilize high-carbohydrate diets and the potential harmful effects of consuming such diets on feline health, increasing the risk of obesity and diabetes.

This belief has led to a broad debate ranging from the need to reduce the inclusion of carbohydrates in cats’ diets to the idea of avoiding them completely, replacing commercial balanced food with alternative diets that have a high protein content (Verbrugghe and Hesta, 2017; McKenzie, 2022).

Based on the above, the question arises: Are carbohydrates truly harmful to cats?

»In the following paragraphs, we will attempt to answer this question by discussing the scientific evidence that supports an affirmative response.

Carbohydrates: Structure and Function

Carbohydrates (CHO) are molecules composed of carbon, hydrogen, and oxygen, classified into monosaccharides, disaccharides, oligosaccharides, and polysaccharides.

Monosaccharides, such as glucose, galactose, and fructose, are the simplest and can be absorbed without digestion.
Disaccharides (maltose, sucrose, lactose) are made up of two monosaccharides and are easily digested.
Oligosaccharides, with three to nine units, are resistant to digestion and are fermented in the large intestine.
Polysaccharides include starch, cellulose, and glycogen, serving as sources of energy and structural support.

Starch and glycogen are polymers of glucose linked by α-glucosidic bonds and serve as energy reserves in plants and animals. In contrast, cellulose is a polymer with β-(1-4) bonds, providing rigidity to plant cell walls.

Dietary fiber, which includes cellulose, hemicellulose, pectins, and other compounds, is key to intestinal health.

Dogs and cats do not digest fiber, but in the colon, it is fermented by the microbiota, producing volatile fatty acids (VFAs) such as acetic, propionic, and butyric acid.

Soluble fiber, fermentable in the large intestine, includes hemicelluloses, pectins, gums, and mucilages. Insoluble fiber, such as cellulose and lignin, is less fermentable and contributes to intestinal transit and feces formation.

The VFAs resulting from fermentation have multiple benefits:

Propionic acid modulates cholesterol synthesis and is a gluconeogenic precursor.

Acetate participates in fatty acid synthesis and regulates satiety.

Butyric acid acts as an energy source for colonocytes, has anti-inflammatory properties, and offers protection against colon cancer.

Insoluble fiber also regulates fecal consistency, promotes satiety, and reduces the energy density of the diet, which is beneficial for animals prone to overweight. Commercial pet foods often combine soluble and insoluble fibers to optimize their benefits.

While carbohydrates (CHO) are an energy source for many animals, the question arises about their relevance in the diet of the domestic cat, given its carnivorous nature.

This raises the issue of whether cats truly need added CHO in their diet or if they can do without them without affecting their health.

References

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