By Jean Hofve, DVM

A reader recently emailed us to ask how she could help her cat lose weight. Indeed, obesity is a serious problem for our feline friends. Many serious health problems can result from obesity, such as arthritis, diabetes, liver disease, heart failure, and kidney disease.

In most feline cases, obesity occurs when tasty, high-carbohydrate food is available 24 hours a day. Single cats may eat out of boredom; when there are multiple cats, when one eats, the others may be inspired to also eat, just to keep the playing field even. (Vinnie, on the right, is one of 6 cats; he may eat a little more than his fair share–but he’s a little shy about it!)

Research has shown that, left to their own devices, cats will “nibble” from a bowl of dry food up to 20 times a day. The researchers conclude that this is “normal” behavior. Well, it may be common—especially when cats are left alone in a cage with nothing else to do!—but it surely isn’t “normal.”

As carnivores, cats are designed for a feast-famine lifestyle. They have a large stomach and short intestinal tract that can take in a large meal and process it quickly. Think about all those nature shows on Animal Planet. The big cats make a kill, stuff themselves until they can’t take another bite, sleep for a couple of days, then go out to hunt again. Our domestic cats are, anatomically and physiologically, identical to their big cat cousins. Clearly, the “grazing” lifestyle is not natural for cats of any size!

When cats “graze” on dry food, many problems will result. First of all, dry food is dehydrating, and thus contributes to bladder and kidney problems.

Also, most dry cat foods contain from 30-55% carbohydrate. Cats use mainly protein and fat for energy, unlike humans who can utilize carbs directly. This means that the carbs in a cat’s diet are basically unusable, providing only calories and little or no nutrition. And we know what happens to excess calories—they get converted to fat!

Another problem with carbs is that they cause wide swings in insulin. Over time, this can lead to diabetes. One researcher bluntly calls dry cat food “diabetes in a bag.” Studies have repeatedly proved that most diabetic cats will reduce or even eliminate their need for insulin shots if they are put on a low-carb diet.

The other major issue with dry foods is the processing. The ingredients are subjected to high heat twice during the manufacturing process, which can denature proteins and potentially trigger food allergies.

The famous “Atkins Diet” is actually ideal for cats. It’s high in protein and fat, and also high in moisture—which is important for cats’ urinary tract health. The “Catkins” diet typically consists of either canned cat food or low-carb homemade food. This diet is the key to weight loss for your tubby kitty. Feed as much as she will eat in 1/2 hour, two or three times a day. A handful of cats will initially gain weight on the Catkins diet, but nearly all cats will ultimately re-regulate and lose weight easily, and more importantly, in a healthy way.

When choosing canned foods for your feline pal, in general stay away from those that contain “by-products”, giblets, or large amounts of fish. Also, some pop-top cans have been linked to the development of hyperthyroidism. This is thought to be associated with BPA in the can lining. Some manufacturers are removing BPA from their products, but the situation is, at the moment, in flux. A homemade diet avoids this issue.

A word about the new “low-carb” and “no grain” dry cat foods. While they are clearly a step up from the high-carb brands, they are still not so great for cats. These high-protein dry foods are even more dehydrating than regular dry foods; and they are still heat-processed. “No-grain” foods may simply substitute starchy vegetables like potatoes or peas, which are as bad or worse, as carbohydrates go. Cats will still gain weight if the food is left out all the time.

If your cat is a total dry food junkie, converting her to one of the low-carb dry foods may be a good first step, but the ultimate goal should be to move the cat to an all-wet food diet fed in meals. (For more on how to get your cat on a better diet, see “Switching Foods“.)

For a more detailed report on this issue, see “Fat Cats” in our Bookstore.