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How to Spot Poor Diet in Cats

by Lauren Samet

In this article, we’ll look at what defines a “poor diet” in cats and how you might identify potential signs in your companion animal. 

What Is a Poor Diet in Cats? 

Put simply, a poor diet is one that does not provide a cat with the correct balance of nutrients it needs to maintain good health. 

Put another way, a poor diet is unlikely to keep a cat free from poor health and disease. 

Appropriate macro and micronutrient levels, fluids, and an adequate energy content are all key factors in a suitable balanced diet for an animal. 

Cats require a very specific balance of essential amino acids and other nutrients in their diet to maintain good health. Complete cat foods are designed to address a cat’s specific nutritional needs when the appropriate guidelines for feeding are followed and so they come highly recommended for feeding your pet cat.

Poor diet comes in two forms both of which can cause ill health:

Before we discuss some of the signs of a poor diet in cats, it is important to point out that some of the signs we mention can also be caused by other factors or disease states too. If you see any signs of suboptimal health in your cat, then it is always best to speak to your vet.

The Litter Tray 

The great thing about cats that use litter trays is that it allows an owner insight into their pet’s digestive health. 

As an owner, you should have an approximate idea of what you expect to find in your cat’s daily litter tray. This means that any signs of diarrhoea (loose runny stools), constipation (stools absent from the tray) or anything unusual could be an indicator that something is wrong with your cat. 

If these changes occur around the time of a diet change then there might be a link. A suitable diet for a cat should allow them to produce faeces which are firm but moist with some regularity in a cat’s daily routine. Healthy stools generally indicate a healthy digestive system, which means nutrients are being processed efficiently and the diet is supporting gut health. 

Urination should also be regular. Any signs of an issue here may indicate an urinary tract infections (UTI), which can sometimes be caused by poor diet (e.g., an imbalance in mineral content). Speak to your vet if you suspect your cat has a UTI as they can cause your pet a lot of discomfort and require veterinary care.

Body Condition Score

I mention it often but helping your cat to maintain an appropriate body weight is crucially important for their long-term health. A poor diet is one that cannot maintain a pet at the correct body weight and this can relate to the quantity being fed not just the quality.


The 2020 PDSA Animal Wellbeing Report showed that cats with obesity was highlighted as one of the top five welfare concerns in 44% of veterinary professionals surveyed. The report also suggested that 52% of cat owners were not sure what their cat weighed. 

Excess body weight in pets is a problem responsible for a myriad of health problems. If your cat is overweight and the cause is overfeeding then unfortunately your cat is not being fed an appropriate diet because the diet is not supporting their long-term health. A diet is not just about what you feed but how much of it you feed, which includes all the little extras like treats and table scraps too.


Underfeeding is much less commonly seen nowadays when owners purchase and feed commercial cat diets daily according to feed guidelines. Weight loss in cats is equally a hot topic among veterinary specialists but often this is less to do with the diet quantity and more to do with a medical issue, old age, or loss of appetite.

Cats that are underfed from a young age may experience slower rates of growth and could be at risk of exposure to dietary deficiencies if not being fed the right amount of a complete diet. Meanwhile, older cats can struggle with absorbing enough nutrients from their diet, which can lead to weight loss and muscle wastage if a long-term issue. Diets specifically formulated for senior or geriatric cats can be beneficial to this because they should include higher levels of nutrients and more easy digestible ingredients, making nutrient absorption more efficient.

If you are concerned whether your pet cat is not the correct weight for their size, then please speak to your vet to find out more information and what you can do to support their health.

A Dull Greasy Coat and/or Dry Flaky Skin 

As cat’s need access to several essential nutrients in their diets, signs of a poor diet can manifest quite quickly through the health and condition of their skin and coat. Stress, allergy, diet, and hydration status can all impact a cat’s skin and coat condition and can possibly lead to a change in grooming habits, issues with hairballs, hair thinning, loss, and dry flaky skin. Additionally, if skin renewal is not supported by their diet then wounds and cuts may take longer to heal, and your cat may be more vulnerable to skin-based parasites like fleas, which can then cause greater damage. 

Occasionally dietary allergies may appear evident through a pet’s coat, grooming behaviours or increased itching and scratching of certain parts of the body. If you think this may be an issue for your pet then speak to a vet for advice and seek advice on hypoallergenic diets for cats.

Nutritional risk factors for poor skin and coat condition include low or poor quality fat or protein content, poorly digestible nutrients or ingredients, and nutrient imbalance that can inhibit the absorption of others.

A healthy diet containing the correct balance of fats, oils, proteins, amino acids, vitamins and minerals should support your cat’s immune system, skin repair and renewal, as well as sebaceous oil production, which keeps skin hydrated and supports a healthy coat. 

Fun Fact: These sebaceous oil glands are part of the cat’s scent-marking system and are present in high numbers on the face, chin, neck, paws and tail area. This is often why cats like to rub their faces and necks against surfaces - including us humans!

Changes in Behaviour 

The above signs of poor diet in cats already suggests they may undergo a change in toileting or grooming habits if their health is compromised by diet. However, there are other behavioural signs also that may suggest their diet is not optimal:

A change in drinking habits – Changes in your cat’s thirst may indicate an unbalanced micronutrient content in their diet among other things. Excessive drinking can also be a sign of Diabetes Mellitus, a chronic health condition discussed in more detail below.

Signs of pain – Gastrointestinal discomfort or pain may lead to your cat behaving unusually, for example hiding more, seeming less pleased to have attention, or being more vocal than usual. If you suspect pain in your pet, no matter the cause, always seek veterinary advice as soon as possible to avoid them suffering unnecessarily.

Chronic Health Conditions and a Shorter Life Span

One example of a chronic health condition caused by poor diet is Diabetes Mellitus mentioned briefly above. Diabetes is caused when the cat’s body is unable to control its blood sugar levels via insulin produced by the pancreas. This may be due to a lack of insulin being produced (Type 1 diabetes) or the body becoming resistant to it (Type 2 diabetes). Diabetes in cats can lead to loss of sight, kidney failure, and arthritis and should be avoided where possible at all costs via support from a balanced diet and not allowing your cat to become overweight.

Another example of a chronic health condition in cats caused by poor diet is dilated cardiomyopathy due to taurine deficiency. Taurine is an essential amino acid to felines and therefore is an essential component in their diets. This deficiency was once common in cats, however, it is much less common these days thanks to supplementation in all complete cat food diets. However, be aware that this health condition is still an issue for cats if homemade or raw diets are fed without appropriate supplementation.

A poor diet does not support a cat’s health and immunity and can be responsible for disease states which may shorten the lifespan of your pet. By providing your cat with a balanced, nutritious diet and keeping them at a healthy weight you can promote the longevity of your pet and perhaps more importantly the quality of their life.


There are several signs that a cat may not be receiving an appropriate diet to support their health, however, this article is not an exhaustive list and does not suggest that there are not other causes for the signs mentioned here. 

If you notice any signs of sub-optimal health in your pet it is always best to speak to a veterinary professional. Equally, if you have any concerns about the quality or nutritional content of your pet’s food, then responsible pet food manufacturers should be willing and able to assist with any questions and queries you may have.

People’s Dispensary for Sick Animals (2020) PAW REPORT 2020: The essential insight into the wellbeing of UK pets (10th Ed.) [online]. Available at: https://www.pdsa.org.uk/media/10540/pdsa-paw-report-2020.pdf 
Rand, J. S., Fleeman, L. M., Farrow, H. A., Appleton, D. J., & Lederer, R. (2004). Canine and feline diabetes mellitus: nature or nurture? The Journal of Nutrition, 134(8), 2072S-2080S.