Hard food (kibble) is not inherently bad for cats, but it does come with trade-offs that matter depending on your cat’s health. The biggest concern is hydration: dry food contains roughly 10% moisture compared to about 75% in wet food, and cats are notoriously poor drinkers. For most healthy cats, kibble is a perfectly fine part of the diet. For cats prone to urinary problems or kidney issues, though, that low moisture content can become a real problem.
The Hydration Problem
Cats evolved as desert animals that get most of their water from prey. A mouse is about 70% water, so a wild cat’s kidneys rarely need to work overtime to stay hydrated. Kibble flips that equation. When a cat eats only dry food, it has to make up the difference at the water bowl, and many cats simply don’t drink enough to compensate.
This matters most for urinary tract health. In one study comparing cats with lower urinary tract disease, clinical signs recurred in 39% of cats fed dry food compared to just 11% of cats fed canned food. The reason is straightforward: more water intake means more urine volume, which dilutes the minerals that can crystallize into painful stones. Cats form struvite stones without any infection involved, so diet and hydration are the primary levers for prevention. For cats already diagnosed with urinary issues, veterinarians typically recommend switching to canned food specifically to increase water intake.
Chronic kidney disease follows a similar logic. As kidney function declines, cats lose the ability to concentrate their urine, so they need more water just to flush out the same amount of waste. Canned food becomes a practical way to sneak in extra fluids. For healthy cats with no kidney or urinary history, kibble’s low moisture is less of a concern, especially if your cat drinks water readily.
The Dental Health Claim
One of the most common arguments in favor of hard food is that it cleans cats’ teeth. There’s some truth to this, but less than most people assume. Research does show that cats eating dry food tend to accumulate less plaque and calculus than cats eating only wet or soft food, particularly on the front teeth of younger cats. The abrasive texture of kibble provides a mild scrubbing effect as cats chew.
The benefit has limits, though. Cheek teeth (premolars and molars) still score higher for dental disease even in cats eating dry diets, and the advantage shrinks as cats age. Standard kibble isn’t a substitute for actual dental care. Dental-specific kibble, which is designed with larger pieces and particular textures that force more chewing contact, performs significantly better than regular kibble. Adding dental chews to any diet, wet or dry, also reduces plaque and calculus buildup. So while hard food offers a small dental edge over soft food, it’s not enough on its own to keep your cat’s teeth healthy.
Carbohydrates and Obligate Carnivores
Cats are obligate carnivores, meaning they need nutrients found primarily in animal tissue. Their wild ancestors ate diets high in protein, moderate in fat, and minimal in carbohydrates. Dry cat food, by necessity, contains significantly more carbohydrates than a cat would encounter in nature. In UK commercial dry foods, about 36% of calories come from carbohydrates, used mainly because cooked starch is what holds kibble together and keeps it from crumbling. Common sources include grains, potatoes, and legumes.
This has led to widespread concern that kibble causes obesity or diabetes in cats. The evidence is more nuanced than the fear suggests. A large meta-analysis found that dietary carbohydrates, across a wide range of inclusion levels (roughly 3% to 57% of calories), were not a significant risk factor for increased body fat, fasting insulin, or blood sugar in cats. Moderate carbohydrate levels had no measurable effect on fasting glucose. Cats can digest and metabolize cooked starches reasonably well, even if they have no dietary requirement for them. There is no minimum carbohydrate requirement for cats, but that doesn’t mean carbohydrates are toxic to them either.
The more practical concern with kibble and weight gain is calorie density. Dry food packs a lot of calories into a small volume, making it easy to overfeed. Free-feeding (leaving a bowl of kibble out all day) is a common contributor to feline obesity, not because the carbohydrates themselves are uniquely fattening, but because portion control is harder when food is always available.
What’s Actually in the Coating
If you’ve ever noticed that your cat goes wild for a specific brand of kibble, the flavor coating is a big reason why. After kibble is extruded and baked, manufacturers apply palatant coatings to the outside. These typically include animal fats, protein digests (enzymatically broken-down animal tissues like poultry, pork, or beef), and yeast extracts. The fat enhances mouthfeel and releases aromas, while the digests provide intense meaty flavor.
Flavor enhancers are the single most common palatant category in dry pet food launches. Some formulas also use amino acid and sugar combinations that create meaty aromas through the same chemical reaction (the Maillard reaction) that makes grilled meat smell appealing to humans. None of this is necessarily harmful, but it does mean kibble is engineered to be highly palatable, which can contribute to overeating if portions aren’t controlled.
When Kibble Works and When It Doesn’t
For a healthy adult cat at a normal weight with no urinary or kidney issues, a complete and balanced dry food can be a perfectly appropriate diet. It’s convenient, shelf-stable, and typically less expensive per serving than wet food. It offers a modest dental advantage over soft food alone. Nutritionally, a well-formulated kibble meets all of a cat’s requirements.
Dry food becomes a poor choice when hydration is critical. Cats with a history of urinary crystals or stones, cats with kidney disease, and cats who simply don’t drink much water on their own all benefit from the extra moisture in canned food. If your cat has had even one episode of lower urinary tract disease, switching to or incorporating wet food can cut the chance of recurrence by more than half.
Many veterinarians and nutritionists suggest a mixed approach: feeding both wet and dry food, either combined in the same meal or offered at different times of day. This gives your cat the hydration benefits of wet food, the modest dental benefit of kibble, and dietary variety. Cats tend to appreciate novelty in their food, so rotating between textures can also help with picky eating. The key is ensuring that whatever you feed is labeled as complete and balanced for your cat’s life stage, whether it’s wet, dry, or a mix of both.