Almost Like Starving Your Cat, This Is Harmful in so Many Ways

fat cat

Story at-a-glance

  • If your cat is overweight, it’s not a good idea to offer a high-fiber “weight loss” dry diet
  • High-fiber kibble blocks absorption of crucial nutrients, is much too low in moisture content, and research shows cats eat less, lose weight and maintain healthy body composition when fed moisture-rich diets
  • For overweight cats, I recommend a moisture-rich, homemade, fresh food diet fed in carefully measured portions, and very limited treats
  • It’s equally important to help your overweight cat get at least 20 minutes of high-intensity exercise each day
  • Cats must lose weight very gradually to prevent a potentially fatal liver condition

By Dr. Karen Shaw Becker

Recently, researchers at the University of Illinois, with financial support from Nutro (a processed pet food manufacturer) published a study titled “Effects of weight loss while feeding a moderate-protein, high-fiber diet on body composition, voluntary physical activity, and fecal microbiota of overweight cats.”1 The study involved eight neutered male, overweight cats, and the researchers reported three primary findings:

  • It’s possible to help cats lose weight by gradually reducing their daily food intake over a period of several weeks
  • The cats’ fecal microbiota changed as they lost weight, with some bacterial groups increasing in number while others decreased, which could indicate positive health effects such as lower inflammation
  • The cats’ weight loss didn’t result in measurable increased voluntary activity, even though they were housed together in a large room with toys and cat towers for up to 22 hours each day

If Your Cat Needs to Lose Weight, Don’t Go This Route

While I’m happy to see additional research on feline health, I take issue with this study for its use of a high-fiber dry diet. In general, it annoys me to see research into how well a particular species of animal can digest food they were never intended to eat in the first place.

The theory behind fiber-filled diets is that they make pets feel full. The problem, however, is they’re not being “filled up” at the cellular level where it really counts. In a 2012 study published in the Journal of Animal Science,2 researchers showed that fiber blocks absorption of crucial nutrients into the small intestine. It acts as a barrier, preventing trace minerals, vitamins and antioxidants from being absorbed into the body.

Chronic deprivation of nutrients to the cells can result in feelings of constant hunger. This is because your carnivorous kitty isn’t getting enough protein to adequately sustain her biology. The constant hunger prompts many pet parents to feed more food. The end result is a pet that is still fat (and often fatter), but at the same time undernourished.

Next to water, protein is the most important nutrient for your cat. Every cell of her body requires protein and when she doesn’t get enough of this essential nutrient, a host of negative side effects can occur.

In addition, cats aren’t built to digest carbohydrates (which include fiber) efficiently. They lack the necessary enzymes to break down and digest fiber or turn it into energy. The majority of starch coming from carbs in a cat’s diet ends up stored as fat. Given the ingredients in dry cat food, it’s easy to see from a physiological standpoint how cats fed kibble become overweight in the first place.

Another problem with kibble — all kibble — is lack of moisture, which is extremely detrimental for felines. Cats don’t have an efficient thirst drive like dogs and other animals. Their bodies are designed to get most of the water they require from their diets, and kibble can’t handle the job.

If your cat isn’t getting sufficient moisture from her food, she’s going without. You won’t find her at her water bowl lapping up huge quantities of the wet stuff to compensate for lack of moisture in her diet. This puts her in a state of constant, chronic, low-grade dehydration, which over time can contribute to major organ failure and chronic constipation.

Moisture-Rich Diets Help Cats Lose Weight Naturally

A 2011 University of California-Davis study found that cats eat less, lose weight and maintain healthy body composition when fed moisture-rich diets.3 The researchers concluded that canned (wet) diets result in cats voluntarily eating less and a corresponding reduction in body weight.

Further, nutritional content and digestibility were not compromised, which as I mentioned is a big concern with dry cat food formulas. In addition, six cats involved in a concurrent palatability study "greatly preferred" the canned diets to kibble. These study results make perfect sense because cats in the wild don't have problems with overweight or obesity. They hunt and eat their natural prey, which contains nutrients vital to their survival, including a high percentage of water.

It stands to reason that when the kitties in the UC-Davis study were fed food closer in digestibility and nutrient content to a species-appropriate diet, they needed fewer calories to feel full. They lost weight naturally without compromising healthy body composition.

The Diet I Recommend for Overweight Cats

Pet foods high in carbohydrates — typically kibble — are the biggest cause of obesity in both cats and dogs. Your kitty needs food high in animal protein and moisture, with low- to no-grain content.

A nutritionally balanced, high-quality fresh food diet is the best choice for pets who need to lose weight. It's important to adequately nourish your cat’s body as weight loss occurs, making sure his requirements for key amino acids, essential fatty acids and other nutrients are met.

The key to healthy weight loss is to meet your cat's unique nutritional requirements through a balanced diet but feed less food (portion control), which forces his body to burn fat stores.

My recommendation is a moisture-rich homemade fresh food diet, comprised of lean meats, healthy fats and a few fibrous vegetables as the only source of carbohydrates. Also be sure to calculate kcal (kilocalorie) requirements for your cat’s ideal weight, measure his food portions using a measuring cup and drastically limit treats (be sure to include treats in his total daily calorie count).

I recommend setting aside a small portion of homemade food that can be rolled into tiny pea-sized bites and used as treats throughout the day. Another option is homemade chicken jerky (I don’t recommend commercial jerky treats, as many have been linked to pet illnesses).

In the beginning days of a gradual transition to his new normal way of eating a better diet in smaller quantities, it’s almost a sure bet your cat will try to convince you to feed him more of what he wants. This is the time for tough love, so distract him with playtime, petting, brushing or a walk outdoors if he’s willing.

Given enough time and patience, most kitties can successfully make the change to a healthier diet and smaller portions. However, since it’s dangerous for felines to go without eating, it’s important to ensure your cat doesn’t simply refuse to eat as a reaction to a new or different diet.

This is especially true for overweight cats, because they can quickly develop a life-threatening condition called hepatic lipidosis triggered by a sudden loss of appetite or a sudden cutback in caloric intake. As long as the transition to a better-quality, reduced-intake diet is very gradual (see my part one and part two videos on how to win the healthy food battle with your cat) and he’s eating enough, stay the course. You won’t be sorry!

Indoor Cats, Especially Fat Ones, Need Encouragement to Exercise

It’s no surprise that the cats in University of Illinois study didn’t voluntarily start to exercise. Like dogs, most adult cats, regardless of body condition, need an incentive to get moving — which is where you come in.

Consistent exercise, including at least 20 minutes of high-intensity activity will help your cat burn fat and increase muscle tone. Make sure he has things to climb on, like a multi-level cat tree or tower. Invest in a laser toy, either a very inexpensive, simple one or something a bit more sophisticated like the Frolicat®.

When considering other feline diversions, think like a hunter and choose toys and activities that appeal to your cat’s stalking instinct. I recommend eliminating food bowls and hiding meals in food-dispensing "mice" placed around the house, forcing your cat to go look for food, an activity that engages his brain, body and palate. And don’t overlook old standbys, either, like dragging a piece of string across the floor in view of your cat.

Ping-pong balls are another oldie but goodie, along with bits of paper rolled into balls, and pretty much any light object that can be made to move fast and in unanticipated ways. For more ideas on how to challenge your cat both physically and mentally, take a look at my interview with cat behaviorist Jackson Galaxy.

I also recommend walking your cat in nice weather using a harness. This gets him out into the fresh air, stimulates his senses and gets his paws in direct contact with the ground. An alternative is a safe, fully enclosed porch or patio area that prevents him from getting out and other animals from getting in.



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