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Maintaining a healthy body weight is a critical aspect of overall health, yet obesity continues to grow among cats, dogs, and even people. Obesity is a disease often accompanied by multiple comorbidities. This is unfortunate. Excess body weight is deleterious to feline health and longevity, and prevention is relatively simple.
For an obesity assessment, veterinarians use a 9-point scoring system called the Body Condition Score, where 1 is emaciated and 9 is fatter than you can imagine. A score of 4 to 5 is healthy. Every point above 5 equates to about 10% overweight. It’s pretty simple to find a body condition score chart on the internet, but the Cornell Feline Health Center also has a free app called “Purrfect Weight” for iPhone/iPads that can help, available at Apple’s App Store.
What Causes It
No matter how you twist it, weight management is a matter of calories in (food) and calories out (exercise). Achieving a healthy balance maintains a healthy weight and body condition. (And don’t try to blame it on a low thyroid condition, as hypothyroidism is rare in cats.) But cats do have predisposing factors that increase their risk for obesity, including:
- Indoor living, as indoor cats tend to have a less-active lifestyle than cats who go outdoors
- Spaying and neutering, but this is not a call to stop spays and neuters
- Free feeding dry food, which makes it impossible to manage intake
Genetics, although this should never be used as an excuse
Why It Matters
Obesity is far worse than lugging around a few extra pounds. Fat cells, called adipocytes, are active molecules that produce biological compounds with potentially harmful effects, especially when present in the abnormally high amounts associated with obesity. Some of these compounds, called cytokines, lead to chronic inflammation. Others interfere with normal insulin function, resulting in a predisposition to diabetes.
Areas compressed by fat have a decreased blood flow. Excess fat interferes with lung expansion, resulting in lower circulating oxygen and higher carbon dioxide levels. When cells suffer oxidative stress, all kinds of pro-inflammatory mediators are released. These mediators combine with the cytokines described above to create chronic, widespread inflammation in the body.
And obesity costs you money. You’re buying excess food, and you’re setting your cat up for long-term diseases that can negatively impact quality of life and lifespan and be expensive to treat.
Those Comorbidities
Diabetes in cats is similar to type 2 diabetes in humans, in that there is resistance to insulin at a cellular level and decreased insulin production. This disease can be promoted by the metabolic derangements caused by substances secreted by those excess adipocytes we mentioned earlier. Managing a diabetic cat requires a big commitment: usually twice-daily insulin injections, special diets, and careful monitoring of food intake and activity levels. All of this, and the cost associated with it, can be avoided by addressing and/or preventing obesity.
Constipation is an uncomfortable condition that can become so severe that a cat cannot defecate at all, and simple enemas may not be enough to move the bowels. This is when constipation becomes life-threatening obstipation. Obstipated cats typically end up under general anesthesia for large-volume enemas and manual extraction of feces.
Feline lower urinary tract disease (FLUTD) and bladder stones are common obesity comorbidities. The reason isn’t clear, but obese cats arrive at the veterinary office with urinary tract issues far more often than lean cats. This comorbidity is so common that there are prescription diets for it.
Osteoarthritis is partially due to the excess stress on the joints and cartilage that the extra weight causes, but those pro-inflammatory compounds the adipocytes release are guilty too. Obese cats are particularly prone to elbow issues including arthritis, tendonopathies, and hyperextension injury. Arthritis in the hips and knees is common.
Skin problems may occur because fat cats cannot reach certain places and are not comfortable holding the posture necessary to groom for long. Seborrhea oleosa-sicca, a dandruff characterized by both greasy and dry flakes, is common and can lead to bacterial skin infections. Treatment involves medicated baths.
Painful, ulcerative moist dermatitis around the vulva in obese female cats can also occur. The excess fat creates deep skin folds that trap moisture and bacteria, and infection can set in quickly. If you have an obese female cat, you need to provide hygienic cleansing until she can reach back there to clean herself again.
Hepatic lipidosis, or fatty liver syndrome, can be fatal. If your obese cat ever suffers an illness that results in anorexia for more than a day or two, rapid metabolism of the excess fat can quickly overwhelm the liver and cause it to fail. These cats present with jaundice (yellow discoloration of the eyes, gums, and skin) and require intensive care. In addition to diagnosing and treating the inciting illness, these cats often require indwelling feeding tubes to stop the negative calorie balance resulting in fat mobilization. It’s a big deal, and again, avoidable in many cases by maintaining a healthy body weight.
Hypertension is common in obese cats. Untreated hypertension can cause acute blindness and other problems, including heart, brain, and kidney diseases. If your cat is obese, ask for a blood pressure check.
Anesthetic risk increases exponentially with those extra pounds. While the risks of anesthesia can be mitigated, it is never without risk. As discussed, obese cats often suffer at least some degree of cardiovascular and respiratory compromise. Additionally, their excess fat makes accurate drug dosing a challenge.
Shortened lifespan has been documented in obese cats. We all want our cats to live happily and healthily for as long as possible, so let’s get into the formula for weight loss.
The Formula
First, because losing weight too quickly is dangerous (remember hepatic lipidosis), you should involve your veterinarian, who will take a thorough history—including diet type and amount, lifestyle, and snacks/treats—and a physical exam with any indicated medical workup.
The goal is to lose no more than 1% to 2% of their bodyweight per week, so for some cats it could take about a year to get them down to a healthy weight.
With a calculator in hand, it’s easiest to determine the recommended 1% to 2% reduction. First, convert your cat’s weight in pounds to ounces. Multiply your cat’s weight in pounds by 16 (there are 16 ounces in a pound). Note: If you have a scale at home, it’s easy to weigh your cat. Weigh yourself while holding the cat, then weigh yourself alone. Subtract your individual weight from the total.
So, if your cat weighs 15 pounds, multiply 15 by 16 and you get 240 ounces. Multiply the 240 by 0.01-.02 (which is 1% to 2%), and you get 2.4 to 4.8 ounces. A healthy weight loss for this cat would be about a quarter of a pound (4 oz.) per week.
Monitor your cat and recalculate this at least once every one to two weeks as your cat continues to lose weight. If he has lost more than 2% of his body weight, increase his calorie allowance a tiny bit. If he’s lost nothing, decrease it a tiny bit. Always work closely with your veterinarian in devising and monitoring a weight-loss plan for your cat.
Calories In
A prescription diet formulated for healthy weight loss is a good choice. These diets are typically “nutrient dense,” meaning they pack more essential protein, vitamins, and minerals into each morsel, so that your cat doesn’t suffer nutrient deficiencies while losing weight. Feeding less of a maintenance diet will result in weight loss, but it potentially deprives your cat of appropriate amounts of essential nutrients.
If the cost of the prescription diets is a concern, remember you will be feeding less, which will offset some of the cost. Otherwise, consider a high-quality over-the-counter weight-loss cat food from your pet-supply store.
Many veterinarians prefer a high-protein, low-carb approach to weight loss, as opposed to the original high-fiber, low-fat approach. This diet may be more in line with the cat’s natural diet (mice, birds). Cats are carnivores, adapted to utilizing mostly protein and fat as their energy sources, and providing enough protein ensures that cats will not lose the healthy lean muscle mass they need.
Feeding canned food instead of dry food more frequently results in successful weight loss. The higher water content in canned food means your cat can eat a larger amount per meal, so she feels fuller and more content after eating. This method often segues into less begging between meals and helps both you and your cat to stick with the program. If you’re thinking about adding water to your cat’s dry food, think again. You would likely have to add four to five cups of water to each cup of dry food to reach the moisture percentage in canned food.
Calories Out
There are lots of ways to encourage exercise in cats, beyond the classic laser-pointer play we’ve all engaged in. Some other ways might be a little sneaky (but effective), like moving the food bowl to different locations in the house every day so he needs to go look around for it.
You can divide his meals up into little brown bags you hide around the house. This not only gets your cat moving around, it’s also a great way to satisfy your indoor cat’s natural hunting instincts. He has to find the food source and rip into the bag to eat.
Commercial puzzle feeders for cats help by making your cat work a bit to get the food. If you’re feeding dry food, toss some of the kibble on the stairs. A bird feeder outside a window can get your cat moving and grooving.
If you feel you can safely get your cat some outdoor excursions (see “Teach Your Cat to Walk on a Leash” on p. 6), you can increase activity and your cat’s enjoyment. For more ideas, look at The Ohio State’s Indoor Pet Initiative website (indoorpet.osu.edu).
The bottom line is, obesity is a devastating disease that is preventable. While treatment can be challenging, with loving care and commitment from you, and help from your veterinarian, getting your cat to a healthy weight is an achievable goal.
What You Should Do
- Weigh your cat periodically and compare his physique to a body condition sheet or our app
- If you note excess weight, use our formula to ensure a 1 to 2% weight loss per week
- Increase the cat’s activity (play with him more!)
- Make a veterinary visit to enlist your veterinarian’s help and expertise
Skinny and Not-So-Skinny Housemates
A multi-cat household can be challenging. You will never get one cat to lose weight if food is left out all the time for the others. You will need to have scheduled, separate meals for all resident cats. An alternative is purchasing a commercially available radio-tagged feeder, where each cat wears a tag that only opens his individual bowl when he approaches the feeder. It’s pretty high tech and expensive, but it can be effective. Or, you can get creative and invent something like a “Slender Cats Only” food house. This would be a box with a narrow slit cut in it, such that only slender cats can enter.
