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The Mistake Many Owners Make When Their Older Cat 'Shrinks'

It's not uncommon for older kitties to waste away and become 'the incredible shrinking cat' as they age, simply because their ability to digest dietary fats and protein efficiently wanes. But the most obvious solution could be a tragic mistake. Here's what I recommend feeding older cats.

shrinking kitty syndrome


  • Many kitties become “the incredible shrinking cat” as they get up in years; both stress and underlying disease can be factors, but often the problem is diet
  • Older cats, especially those fed a lifetime of ultra-processed cat food, often lose their ability to digest dietary fats and protein efficiently, which is a major contributor to weight loss
  • The dietary answer for most aging cats isn’t to reduce protein intake to decrease organ stress; the answer is to feed a moisture-rich diet of high-quality animal protein, along with appropriate supplements
  • Older cats whose appetites have dropped off can and should be enticed to eat more

Many cats seem to thin out as they get older, and in fact, research shows that a decrease in body weight is very common in kitties over 11 years of age.1

There are a variety of reasons for this phenomenon, and while today’s discussion is about dietary considerations, it’s important to realize that other factors, such as stress and certain diseases (including thyroid problems) can also play a role. For more information on those issues, read Shrinking Kitty Syndrome.

Studies show that both protein and fat digestibility decrease in cats after age 10.2,3 Dietary fat contains more calories per gram than either proteins or carbohydrates, so if your senior kitty’s ability to digest fat is limited, it can have a major effect on her ability to extract calories from food.4

Research also shows that about 20% of cats 14 years of age and older don’t digest protein efficiently.5 A compromised ability to digest both fat and protein is likely a major reason senior and geriatric cats lose both fat and muscle mass.

The cause of this phenomenon hasn’t been identified, but in my opinion, long-term consumption (often a lifetime) of ultra-processed cat food containing poor quality, hard-to-digest ingredients plays a significant role.

Reducing Dietary Protein Is the Wrong Answer!

For many years, the veterinary community’s answer to the problem of reduced protein digestibility in older cats was reduced protein diets to mitigate compromised kidney and liver function. However, reduced protein cat food can be a recipe for disaster, because we now know aging cats actually need more protein than their younger counterparts.

In the 1990s, retired veterinary nutritionist Dr. Delmar Finco discovered protein requirements actually increase as pets age. He demonstrated that even in animals with kidney failure, restricting protein didn't improve their health or longevity.6

In fact, Finco's research proved cats on low protein diets develop hypopro-teinemia, which is an abnormally low level of protein in the blood. The cats had muscle wasting, became catabolic (lost both fat and muscle mass), and lost weight. The more protein was restricted, the sicker these kitties became.

Finco discovered it was the level of phosphorus in foods, not necessarily the amount of protein that exacerbated kidney disease, and thanks to his groundbreaking research, veterinary recommendations have changed.

These days, we recommend a diet containing excellent quality (human grade) protein that is highly digestible and assimilable for animals struggling with under-functioning kidneys and livers. We also recommend restricting phosphorus in the diet, but not necessarily protein.

If your cat is in the later stages of kidney failure, as defined by the International Renal Interest Society (IRIS), a reduced amount of protein is suggested, but should still be offered in a high-quality, kidney-friendly fresh food format.

We now know that cats, as true carnivores, require lots of high-quality, human grade animal protein not only to maintain good organ and immune function, but also to maintain healthy muscle mass as they go through life and the aging process.

Not All Protein Is Created Equal

The quality of the protein you feed your senior cat is of utmost importance. Highly digestible and assimilable protein, coupled with high moisture content, is the type of nutrition that causes the least amount of stress on your kitty’s aging organs.

It’s sort of a well-kept secret, especially among ultraprocessed pet food manufacturers, that protein quality is extremely variable. There are highly assimilable and digestible animal proteins (proteins your cat’s body can easily absorb and derive nutrition from), and there are plant proteins that are both biologically inappropriate and difficult to process.

All protein has a biologic value, which is its usable amino acid content. Eggs have the highest biologic value at 100%. Fish is a close second at 92%. Feathers, as you might guess, have zero biologic value. They are technically animal protein, but they are neither digestible nor assimilable.

There are also foods that are high in (plant) protein but biologically inappropriate for cats. Soy is a good example, with a biologic value of 67%. Many popular pet foods contain soy as a protein source, as well as corn. This is an inexpensive way for pet food manufacturers to increase protein content on the guaranteed analysis printed on the label. But because soy and corn are not species-appropriate, they don't belong in your cat's diet.

Since digestion and assimilation are not always measured for pet foods, manufacturers are not penalized for adding protein that has little to no nutritional value for the species of animal eating it. Call your pet food manufacturer and ask if their meat is human-edible quality. “Feed-grade” meat is substantially cheaper (and potentially much less assimilable), which is why 99% of pet food companies use it.

In addition to corn and soy (as well as other grains) that are inflammatory and incomplete proteins for carnivores, there are many other reasons not to feed carbohydrates to cats. Mycotoxins, GMO’s, glyphosate exposure and sugar load (which leads to lifestyle-induced diabetes), as well as obesity and arthritis are all solid reasons to avoid offsetting high quality protein with cheap fillers.

The Diet I Recommend for Most Older Cats

Some foods are metabolically stressful, for instance, grains and potatoes prompt a big insulin release. The nutrition that generates the least amount of metabolic stress for most cats, regardless of age, is whole, unprocessed, organic, non-GMO, and minimally processed (raw or poached). This of course includes human grade animal meat, which should be the foundation of your kitty's diet throughout her life.

Foods that have not been highly processed are the most assimilable for a cat's body. All the moisture in the food remains in the food, whereas foods that have been extruded (most dry food) can have drastically depleted moisture content — as low as 12%.

Dry pet foods only increase digestive and organ stress, so feeding moisture-dense, non-dehydrated foods is essential, especially for cats. Click here to watch my Facebook live on how to wean finicky kibble addicts onto moisture-rich cat foods.

If you can't feed fresh food (raw or gently cooked), second-best is a dehydrated or freeze-dried balanced diet reconstituted with plenty of water or broth. Your cat's kidneys and liver can be further stressed as a result of chronic low-grade dehydration, so all foods served dry can pose a problem long term.

I recommend serving your cat food in its natural state to provide needed moisture, and to ensure the highest level of biologic assimilation and digestion. That means feeding a nutritionally optimal, antioxidant rich, species-specific diet that includes omega-3 essential fats, DHA and EPA.

Moisture is an aging cat's best friend, so encourage yours to drink by offering a variety of glass, metal or food grade ceramic water bowls around the house or a drinking fountain, in addition to minimizing (or preferably eliminating) dry food.

However, if your kitty is addicted to terrible food, adding a whole body supplement, such as Feline Whole Body Support is a good idea. Adding bone broth to a dry food addict’s meal is also a great way to increase hydration and fluid balance.

The most important supplement you can add to assist with digestion and assimilation of nutrients are digestive enzymes. Supplemental amylase, lipase and protease (to help break down carbs, fats and proteins) can dramatically reduce digestive stress as pets age and reduce the likelihood of pancreatitis.

I recommend all older animals take digestive enzymes, as they help process and metabolize food more efficiently and reduce gastrointestinal discomfort. Additional beneficial supplements include SAMe (S-adenosylmethionine) as a safe and effective way to stall mental decline, improve mobility and assist in liver detoxification. Consult your integrative veterinarian for the right dose size.

Periodic detoxification with milk thistle, superoxide dismutase (SOD) and dandelion can also be very beneficial, as can providing super green foods in the form of fresh cat grass to nibble on. Chlorophyll, chlorella or spirulina can also be offered in supplement form to enhance your cat’s detoxification processes.

Medium-chain triglycerides (MCTs) have been shown to be safe for cats and can improve brain energy metabolism and decrease the amyloid protein buildup that results in brain lesions in older pets. Coconut oil is a rich source of MCTs and may also reduce hairball issues. I recommend 1/4 teaspoon for every 10 pounds of body weight twice daily for basic MCT support, if your cat will voluntarily eat it.

For aging kitties who tend to prowl the house at night and vocalize, consider low dose melatonin, which is not only a sedative with a calming effect, but also an antioxidant. CBD can also be of benefit for pets.

Tips for Nourishing a Finicky Feline

If your cat is eating ultra-processed pet food, again, my first recommendation is to try to slowly and safely transition her to a nutritionally balanced, fresh, organic, non-GMO, species-specific diet made with human grade ingredients.

Whether her diet is fresh or processed, however, the goal should always be to make sure your cat eats something several times a day. This may mean adding delicious broths or toppers to her regular food or switching proteins or brands to keep her interested in eating.

Unlike dogs and humans, it's dangerous for kitties to go any length of time without nourishment, as it can lead to a potentially fatal liver disease called hepatic lipidosis.

Many older cats prefer to nibble throughout the day; offering food when they want to eat is a good way to keep calories coming into an aging body. Offer as much food as your cat wants to eat if you’ve noticed weight loss with age.

Keeping your older cat well-nourished can require creativity along with some gentle prodding, and lots of patience. Things you can do to tempt her include:

  • Warming her food to bring out the aroma
  • Offering gently cooked food with a strong smell or topped with a sardine (packed in water)
  • Offering new food from a paper plate in case she's developed an aversion to her food bowl for some reason
  • Offering a small selection of different flavors and textures of canned cat food or home cooked meat or bone broth
  • Enticing her with species-appropriate human food she has enjoyed in the past, such as warm baked chicken or salmon
  • If she's addicted to dry food and refuses everything else, try adding warm water to each meal or add an aromatic enticement like tuna juice, warm goat's milk, chicken broth or bonito flakes

It's also important to make your cat’s mealtime a very low-stress, pleasant experience. Feed her in a calm, quiet environment that is optimally comfortable.

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