Cats are beautiful in all sizes. However, you may very well be concerned about your cat being too skinny, especially when she seems to be eating normally.
Just like being overweight can be an alarming issue, being too skinny can also be a red flag for various underlying health problems in cats.
Several factors may be causing your cat to lose weight or prevent her from gaining weight. These factors can vary based on her age or breed, her activity levels, the food she eats, or any health issues she may be experiencing such as diabetes, hyperthyroidism, intestinal parasites, and so on.
Below you’ll find all these factors explained, as well as information about how to tell if your cat can be considered too skinny and what a healthy-weight cat should look like.
Why Is My Cat Eating So Much but Not Gaining Weight?
Bodyweight is determined by the amount of energy we put into our bodies vs how much we use up. The more we eat, the more weight we will put on. That is unless we are doing enough exercise to use up all of the extra calories we are consuming. For weight loss, the opposite is true. If our bodies are burning more energy than we are providing it through our diets, then we’ll lose weight.
This balance between energy input, energy output, and weight is not solely true for humans. It is true for all animals, including cats. Therefore, you would assume that a cat that is always hungry and always eating would be a fat cat indeed. So, why are some cats always hungry but skinny?
This is all to do with a disruption between energy input and output. For a cat to remain skinny, it must be using more energy than it is gaining through its diet. Therefore, for a cat that is eating a healthy amount, one of the following factors is likely true:
- Something is causing the body to use more energy at its base level than it usually would. In other words, their basal metabolic rate is increased.
- Something is preventing the body from getting the energy from the food it eats and absorbing all the nutrients.
- The food that they are eating is of poor quality, so despite eating a lot your cat isn’t gaining what they need from their diet.
Normal Factors That Inhibit Weight Gain in Cats
In this section, we look at the factors that inhibit weight gain in more detail. The factors listed below depend on your cat’s particular circumstances and her natural traits such as her age, breed, and temperaments. It could be that one, two, or all three of these factors apply!
1. Old Age
Senior and geriatric cats are most prone to losing weight even when they maintain their usual appetite. This is because old age inevitably brings with it metabolic changes and deteriorates its digestive functions. Their impaired digestion means they might not be absorbing all the energy and nutrients from their diet. Despite eating a lot, they’re not benefiting much from it.
Senior cats are also more likely to experience medical problems such as diabetes, hyperthyroidism, and organ failures like kidney disease. These are all health problems that cause weight loss due to symptoms such as diarrhea, vomiting, excessive activity, excessive urination, and muscle loss.
If you see your older cat not eating but drinking, get them in for a checkup with your vet right away.
2. High Activity Levels
As already mentioned, simple math tells us that burning more calories than consumed will lead to weight loss. This usually happens when a cat starts eating less than usual due to physical or psychological distress. However, when a cat eats normally but keeps losing weight, it may have something to do with how active she is.
Activity levels usually depend on a cat’s breed, age, particular temperament, and living situation:
Activity Levels by Age
Kittens and junior cats tend to be more active than older, mature cats. They also need almost twice as many calories that an adult cat requires to grow properly. It can vary from cat to cat, but generally, as younger cats mature, they become calmer. Contrary to popular belief, this isn’t a result of neutering, but a natural course of aging.
If you have a young cat that doesn’t seem to be putting on the weight she needs to as she grows, visit your vet to eliminate any health issues such as intestinal parasites.
Activity Levels by Breed
Some cat breeds are more active than others by default. Breeds such as the Abyssinian, Bengal, Savannah, and Siamese are usually very athletic and active. You may have noticed that these cats appear more slim and fit, like a leopard or a cheetah. This is because they are burning many more calories through all their exercise and are building plenty of muscle along the way.
When compared to these, breeds such as the Persian, Ragdoll, and Maine Coon are more sedentary. They are what we usually call “lap cats” and their physical appearance is quite distinct from the more active breeds mentioned above.
Activity Levels by Lifestyle
Cats that have a chance to go outdoors are also likely to be more active because of their particular living circumstances. When a cat goes outside, she is more alert for danger and has a lot more stimuli to keep her busy and moving.
Depending on the circumstances of her outdoor environment, your cat may be running after a bird or sleeping in a sunny patch. So not all outdoor visits necessarily mean that your cat will be more active than usual. Therefore, outdoor cats can eat more and stay skinny, whereas more lazy indoor cats that don’t move all that much can easily pile on the pounds.
Although these factors affect a cat’s activity levels and the extent of their daily calorie burn, it is still an important issue if she keeps on losing weight. Even when a cat is very active, she should at least be maintaining her weight if she eats well. So, if you are sure that your cat gets all the calories she needs and she’s still losing weight, take her to the vet for conclusive results.
3. Choice of Food
Even though you may have been feeding your cat the same food for years with no problem, it is possible that she may need a dietary change.
Your cat’s current food may not be fulfilling her caloric or nutritional needs as well as you thought. Or your cat may be allergic to an ingredient in the food. I used to see my cat throwing up after eating all the time and it turned out she was allergic to the specific protein in her food. This is why it’s important to read cat food labels carefully and compare nutrient ratios to facilitate a healthy weight gain.
Go for foods that have high amounts of quality protein. Although they should not be eliminated, fiber and carbs should be at a minimum (no more than 2%) because they upset your cat’s digestion. The best hack for having your cat eat high amounts of nutritious calories is to go for very tasty food with high calories of protein and fat.
The most recommended method to achieve this kind of food is to mix dry and wet food. Has your cat stopped eating dry food but eats treats? Mixing wet and dry food is also a smart idea if your cat refuses to give up her beloved kibble. You may also consider adding delicious, nutritious toppers to your cat’s usual food.
However, wet food is often recommended for cats that have issues of weight and appetite loss. This is because wet foods usually have more protein than dry foods. Plus, they have more moisture which helps with proper hydration. It’s also a great option if your cat has dental disease or other oral condition that makes chewing hard kibble painful.
Please consult your vet when going for a change in your cat’s diet. Your vet will do the best job recommending the most fitting food for your cat.
Health Problems That Cause Weight Loss in Cats
Although it is common for senior cats and very active felines to be on the skinny side, you need to be aware of health problems that can cause weight loss in cats. Indeed, when a cat is losing weight even though she eats normally, it is most likely due to the health issues listed below.
1. Gastrointestinal Problems
Gastrointestinal (GI) problems in cats affect their digestive tract and can range from mild to severe. They can be acute, such as being set on by a virus, bacteria, parasite, or toxin. Alternatively, GI distress can be chronic, set on by allergies, cancer, or recurrent infections – especially in older kitties.
There is a huge range of gastrointestinal issues, but some of the more common problems that arise in cats include:
- Internal parasitic infections
- Inflammation of the large intestine
- Cancers in the digestive system
- Obstruction along the GI tract
- Stomach ulcers or ulcers in the intestines
- Inflammatory bowel disease
- Inflammation of the stomach, known as gastritis
Weight loss as a symptom is common for all these gastrointestinal issues. Each impairs normal digestive function in some way. As a result, the body cannot absorb all the energy and nutrients it needs through its diet. Despite eating like normal, this can lead to long-term weight loss if the underlying condition is not treated.
Weight loss is also caused by other symptoms of the disease, mainly vomiting and diarrhea. Cats that are sick or have diarrhea are not absorbing all the nutrients and energy from their food. Weight loss as a symptom is especially common in senior cats that suffer from gastrointestinal disorders. These older felines already have an impaired digestive function, so a GI disease on top of this only exacerbates this.
Many gastrointestinal conditions can also cause a cat to stop eating altogether. Your cat won’t appreciate the digestive discomfort or constant vomiting, so they lose their appetite. Of course, this only makes their weight loss worse! When not consuming as much food as they should do, their bodies become even weaker.
If you notice your cat not eating or drinking for 3 days, this is a medical emergency. At this point, your cat is at risk of dying if you don’t seek professional help. However, even if your cat has diarrhea but seems fine otherwise, it is best to take a trip to the vet. Catching these GI problems early makes treatment much easier. It might be that your cat does just have a funny tummy, but it is always better to be safe than sorry!
Depending on the diagnosis, your vet can recommend treatments ranging from a simple dietary change to a more specialized medication or even surgery.
2. Intestinal Parasites
Intestinal parasites are also considered a gastrointestinal problem because they cause a disorder in a cat’s digestive tract. I wanted to put them under a separate heading because several types of internal parasites may cause unwanted weight loss for a cat. They’re also one of the most common causes of GI discomfort and are worth a closer look at.
Roundworms are the most common intestinal parasite that can cause unwanted weight loss in cats. They live inside your cat’s intestines freely and live off the food your cat eats. This means your cat isn’t getting the nutrients and energy they need, despite eating loads.
Causes of Roundworms
Cats usually get roundworms from contact with rodents and other small animals. Cats have a high chance of ingesting the larvae that are carried by these animals. So, if your cat likes to go outdoors and has a habit of bringing you gifts like mice, she may be at risk of getting roundworms.
Kittens can also get roundworms from their mother’s milk if their mother has roundworms. Roundworms can be particularly problematic in kittens. This is because young cats are still very vulnerable to any type of infection. Moreover, unlike adult cats that are trying to maintain their weight, kittens are trying to grow into strong young adult cats.
Symptoms of Roundworms
If your cat has roundworms, you’ll notice all the following symptoms:
- Weight loss despite eating like normal
- Vomiting and diarrhea
- A dull-looking coat
- Slightly enlarged belly, especially visible in kittens
You can also easily spot roundworms in your cat’s feces. They appear as little stringy worms that are quite easy to distinguish. Just keep in mind that humans can also be affected by roundworms – so be very careful when examining your cat’s stool and take measures to keep your hands clean and out of your face.
Treatment of Roundworms
There is usually no need to worry if your cat has roundworms because it is an easily treatable condition. There are several medications that eradicate roundworms that your vet can recommend to you.
The important thing is to keep in mind that these medications don’t work on the dormant roundworm eggs, but only on mature roundworms. So, your vet will probably prescribe a treatment of a few rounds 2-4 weeks apart to get rid of all the larvae that may still be in your cat’s intestines.
To prevent your cat from getting roundworms in the future, you should adhere to her regular monthly internal parasite medication. It can also help to schedule routine stool checks even if you don’t suspect any problems.
Just like roundworms, hookworms also live in a cat’s intestines. However, unlike free-swimming roundworms, hookworms latch onto the intestinal walls and feed on the blood in the intestinal tissue. Doing so disrupts your cat’s usual digestive function, meaning your cat struggles to absorb all its needs from its diet. This leads to weight loss despite no change in appetite.
Hookworms are often introduced to a cat’s system when she congests the larvae without noticing. Hookworms are usually found in moist and warm environments. Cats that go outdoors in such environments are prone to ingesting hookworm eggs by way of contact with other animals or surfaces. Just like roundworm infections, kittens can also get hookworms from their mother’s milk if she has them.
The most common symptoms of hookworms in a cat is weight loss and an unhealthy–looking coat. Since hookworms feed on the blood of a cat’s intestinal tissue, the most distinct result of hookworm infection is anemia. The digested blood in a cat’s intestines will cause the feces of an infected cat to appear almost black.
Just like roundworms, the diagnosis and treatment of hookworms are also easy. Your vet can easily recognize roundworm eggs in your cat’s feces under a microscope. The treatment takes at least two rounds of administering a medicine named anthelmintic to destroy newly hatched eggs.
Giardia are one-celled organisms that reside in a cat’s small intestine as a parasite. They cause giardiasis, an ailment that results in weight loss, diarrhea, dehydration, and lethargy in cats.
Fortunately, giardiasis is not very common. It usually spreads in poor, overcrowded environments such as shelters and kennels. Cats can pick up the parasite from each other’s infected feces by sharing a litter box or from contaminated water sources.
The diagnosis and treatment of giardiasis are relatively more difficult when compared to worms. Not all cats that have giardia develop giardiasis, but they can still spread it to other cats. However, giardia can be observed in a cat’s feces under a microscope or by testing for antibodies in the feces. Spotting giardia cysts in the feces is harder than spotting worms and several samples may be needed to be conclusive.
Once diagnosed, the treatment usually involves an antibiotic medication called metronidazole. A cat may need several rounds of this treatment because giardia can be resistant. If your cat has giardia, make sure to keep her litter box clean to avoid reinfection. It is also important to separate litter boxes if you have multiple cats so that it doesn’t spread.
Hyperthyroidism is a glandular disorder that can affect any cat but is more common in older cats past the age of 10. Its most distinctive symptom is weight loss accompanied by an increase in appetite. Other symptoms of hyperthyroidism include:
- Excessive thirst and urination
- An increase in activity levels
- Vomiting and diarrhea
- Panting and restlessness
As the name suggests, hyperthyroidism is where the thyroid gland located in the next becomes overactive. This gland is responsible for producing a thyroid hormone known as T4. This hormone is directly involved in metabolism. The more thyroid hormone present, the faster your cat’s metabolism is. This means they burn more energy at rest than they would have done previously. As such, your cat’s appetite will increase, and their weight will decrease.
Since hyperthyroidism causes elevated levels of the T4 hormone in the bloodstream, the diagnosis technique is a blood test. You’ll need to take your cat to the vet for this. However, try not to panic if your cat is diagnosed. Hyperthyroidism is treatable – and it may even be curable if diagnosed early on. Some treatment options include:
- Antithyroid Medication: This is usually an oral medication containing methimazole which needs to be taken daily. The medication might be given as a life-long treatment or to help stabilize your cat before another treatment option.
- Thyroid Removal Surgery: The scientific name for surgical removal of the thyroid gland is a thyroidectomy. Your cat might have one or both glands removed. Without these glands in your cat’s body, they cannot overproduce the T4 Therefore, the surgery is curative.
- Radioactive Iodine Therapy: This is a newer curative treatment option shown to have incredible success rates in cats. It is far less risky and requires less downtime than surgery. Your cat simply needs an injection of iodine which destroys the overactive cells for good.
Diabetes means that a cat’s body cannot produce the necessary amount of insulin to regulate its blood sugar. Diabetes in cats can cause weight loss even though another one of its symptoms is that they eat a lot. This is because their body cannot make use of the nutrients they consume, so they don’t put on any weight. At the same time, they’re never satisfied and so they crave more, causing their appetite to increase.
Other symptoms of diabetes include excessive thirst and urination, both of which cause dehydration, and vomiting. In some cases, there may also be a loss of appetite. This is usually down to poor diabetes control as studies have found consistently high blood sugar can curb your cat’s appetite. Diabetes can also cause your cat to feel sick, putting them off eating. So, if your cat is not eating much but acting normal, diabetes could be why.
While the medical treatment of feline diabetes is insulin therapy, adjusting their diet will also help with the situation. Diabetic cats need to be on a high protein and low carb diet. This is easier for the body to digest and absorb what it needs.
5. Psychological Ailments
Psychological distress is another well-known cause of weight loss in cats. Stress and anxiety in cats can lead to eating disorders like anorexia. Anorexia in cats means a noticeable loss in their appetite that is caused by psychological rather than physical reasons.
If your cat is always hungry but losing weight, stress and anxiety probably aren’t the cause. Still, I wanted to mention this possibility because it may sometimes be hard to tell if your cat is eating normally. This is especially true if you look after multiple cats. Keeping track of exactly how much each cat eats can be one hell of a task! It is possible that your stressed and anxious cat isn’t eating much, while your larger greedy feline is scoffing down the lot.
If you don’t see any behavioral changes other than a loss of appetite, it may still be indicative of underlying stress-related issues. You should take appetite and weight loss very seriously. However, if your stressed-out kitty isn’t eating, this probably isn’t the only indication of stress. Other symptoms include:
- Grooming more than usual
- Increased hiding behaviors
- Acting more affectionate or more aggressive
- Excessive meowing and other vocalizations
- Becoming less tolerant of people
- Reluctance to use the cat flap or litter box
To avoid any psychological distress as a cause for appetite loss, you should make sure that your cat’s eating arrangement is ideal. Set her food in a clean, calm corner of your house that is away from her litter box. There shouldn’t be a lot of foot traffic or distractions near her food.
I’d also recommend feeding your cats in different rooms if there are any conflicts over mealtimes. You can even purchase cat bowls with collar sensors. These are a great way to keep track of exactly what each of your cats has eaten. Then, whenever any changes to their feeding habits do arise, you will notice them straight away!
You should also evaluate your cat’s environment for causes like a big recent change (arrival of a new pet, moving to a new house, change in her usual food) or other constant stress factors such as too much noise, poor hygiene, stale air, and more. Keep in mind, cats are extremely empathic and may even mirror their owner’s mood.
Where possible, you’ll want to remove these stressors so that they don’t affect your cat. Yet this isn’t always possible. If you have moved house, you can’t simply move back to the old one just because your cat doesn’t like it! In these cases, you’ll want to make your home as cat-friendly as possible. Provide plenty of toys, scratching posts, and places to hide. Any changes you do introduce into your cat’s environment in the future need to be done slowly.
What is the Ideal Weight for Cats?
It shouldn’t matter how fat or skinny your cat is as long as they are healthy. And a healthy weight for one cat might be completely different from a healthy weight for another. The age, breed, and sex of your cat all impact what a healthy weight is. Therefore, there is no set ideal number for a cat’s weight.
However, keeping in mind your cat’s age, breed, and health conditions, you may determine a healthy weight range for your cat and make sure she stays within this bracket. But even this can give a false impression. Therefore, a better idea is to determine whether or not your cat is a healthy weight based on their appearance.
So, how can you tell just from looking whether your cat is a healthy weight?
How to Tell if Your Cat Is Underweight
With underweight cats, you can easily see their ribs, spine, and hipbones because they have very little or no fat. Underweight cats have a very deep abdominal tuck, which means that their belly area appears almost hollow. (Although as I’ve mentioned earlier, roundworm infection can make a cat’s tummy enlarged.) Underweight cats will also have little muscle so their legs will appear skinny rather than athletic and muscly.
If you have a long hair breed and can’t distinguish these features easily, you can also try inspecting your cat with your hands. This can be more difficult because unless you have an extremely overweight cat, you can feel their ribs, spine, and hipbones easily. Simply feeling these bones does not mean that your cat is underweight.
So, here’s a trick: if their ribs feel like a very hard bone (like what you feel when you touch your knuckles), then it means there’s no fat around them. If the ribs feel a lot more cushioned (like the inside of your palm), then it may indicate excessive fat. The ideal hardness you feel should be like the back of your hand, slightly padded but not to the point of being squishy.
How to Tell if Your Cat Is Overweight
Unless she is severely obese, distinguishing an overweight cat can be more difficult. This is because the cat obviously won’t have their ribs sticking out. Therefore, you have to look for different indications instead.
Perhaps the most distinguishing visual feature in an overweight cat is that she doesn’t have an abdominal tuck, which means that you can’t see her waist. She will also have a visible belly that may be drooping down depending on how overweight she is. Besides the torso, an overweight cat’s limbs will also appear chunky, and you won’t be able to see much muscle definition.
Look at your cat not just from the side but also from above. With overweight cats, you’ll see obvious protrusions to the sides in the lumbar area. Although, this may also be the case with pregnant cats, so make sure you’ve eliminated that possibility before declaring your cat overweight.
For longhaired breeds, simply try to feel your cat’s ribs. If you can hardly feel them, or if they feel highly padded (like your palm instead of your knuckles), then there may be excessive fat around them. Your cat will need to shift a few pounds to drop back into a healthy weight bracket.
How to Tell if Your Cat Is a Healthy Weight
So, what should a healthy, ideal-sized cat look like? Again, I can’t offer you a scale number because an ideal weight number will vary depending on breed, sex, and age. Just like I’ve explained with under and overweight cats, you can also tell when a cat is at her ideal weight by her appearance.
A healthy cat will appear well-proportioned in all areas of its body. Whether you look at her from the sides or above, she will not show any abnormalities. You won’t notice her belly sweeping the floor, love handles extending from either side, or hollowing of the sides due to low weight. Likewise, the limbs will not be too skinny or too chunky.
You will be able to see the waist of a healthy-weight cat, although her abdomen will not appear tucked or hollow. In fact, there can be a little bit of fat in the abdomen area. This is perfectly healthy, and it is good for cats to carry around a little extra padding.
Moreover, you won’t notice any harshly protruding ribs or clearly defined bones either. However, a healthy-weight cat’s ribs can still be felt. You should be able to feel a little padding over the top of them though, like the back of your hand. They will still feel firm but not too boney like your knuckles.
Remember, weight loss is more or less a gradual process. It may be hard to notice, especially if your cat seems to be eating normally. This is why you should make sure to regularly check your cat’s stools, keep up with her routine parasite medications, and try to track any physical changes like the appearance of her coat, the condition of her teeth, her movement, and so on.
It is also important to keep an eye on any behavioral changes for signs of lethargy, stress, poor self-hygiene, unusual sleeping patterns. These can all indicate that something is wrong with your cat that could be causing them to lose weight and drop below a healthy level.
If you spot any irregularities in your cat’s appearance or behavior, the first thing to do is to visit your vet and get a full check-up on your cat. This will reveal any existing problems and allow you to take action in treating your cat. As weight loss takes time, don’t delay in taking your cat to the vet. There is a chance the disease is also pretty well progressed, so prompt treatment is more important than ever!