How to Spot if my Cat has a Poor Diet

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That well known saying ‘you are what you eat’ certainly applies to cats too! With so much (often contradictory!) cat diet advice available on the internet, choosing the best diet for cats can seem daunting. So, let’s look at the healthiest diet for a cat.

Cat nutrition – the basics

Hungry cat sitting next to empty bowl

Cats need adequate protein (30–45% dry matter for an adult cat), moderate amounts of fat (10-15% dry matter) and enough fibre. They can use carbohydrates as an energy source too. Cats also need vitamins, minerals and essential fatty acids. Of course, we mustn’t forget water! It’s essential that cats have access to fresh water sources at all times, away from their food and litter areas.

Cats are ‘obligate carnivores’, meaning that they need some nutrients which can only be found in meat products. For example, cats cannot make enough of their own taurine, an amino acid found in meat, so they must get enough from their diet. Taurine is essential for eye and heart health, amongst other things. This means cats cannot be vegetarian! However, they also cannot survive on a meat-only diet, as this would lack essential nutrients such as calcium. Remember that in the wild, cats would eat whole carcasses, not just the muscle meat.

The quality of ingredients in the diet is important too, since higher quality ingredients will be more digestible. Low digestibility means that the cat cannot access or use the nutrients, even if they are present, since they aren’t being digested properly.

It’s important to note that a cat’s exact nutritional requirements will also change as they get older, when they’re ill, if they’re pregnant or feeding kittens, and whether they’re indoor-only or allowed outside.  

What is the healthiest diet for a cat?

There’s a lot of information and misinformation out there when it comes to the best diet for cats, so it’s best to take some expert advice when it comes to cat diets.

International Cat Care advises that feeding a good quality complete commercial cat diet is the best option. It is very difficult to ensure a homemade diet is nutritionally complete, so homemade diets should only be considered under the guidance of a veterinary nutritionist. When looking for a commercial diet it’s important to consider:

  • Life-stage: choose a diet that is appropriate for your cat’s life-stage. Kittens have very different nutritional needs from adult cats, as do senior cats.
  • Reproductive status: whether your cat is neutered, pregnant, or lactating will affect their dietary needs, so look for a specially tailored diet.
  • Lifestyle: a sedentary indoor cat will need significantly fewer calories than an active roaming outdoor cat, for example.
  • Whether the diet is nutritionally complete: this will be stated on the packaging. Diets which are not nutritionally complete are known as ‘complementary’ and are usually considered treats. These should not make up more than 10% of your cat’s daily calorie intake.
  • Underlying medical conditions: you can purchase veterinary diets specifically formulated for certain medical conditions, such as diets for elderly cats with kidney disease.

If you need cat diet advice, speak with your vet or vet nurse, who can advise on the best diet for your cat’s individual needs.

What’s the best cat weight loss diet?

Fat cat sitting

Obesity is a growing problem in cats. Obesity increases the risk of heart disease, joint problems, diabetes, skin complaints and can even shorten life expectancy. It can be challenging to decide what and how much to feed a cat on a diet. You can purchase diets specifically aimed at weight loss in cats, which are a great place to start. Some are designed to help your cat feel fuller, and so eat less. If you choose to continue with their usual diet, then you can decrease the amount you are feeding gradually, but you may find that they beg more! Either way, weight clinics run by veterinary nurses are a great way to stay on track!

It’s important to note that weight loss should be slow and steady, since rapid weight loss can be harmful to your cat’s health. As a general rule of thumb, losing 1% of your cat’s total body weight per week is a safe rate of loss.

How can I tell if my cat’s diet is lacking nutrients?

Poor nutrition can come about from feeding a poor-quality diet, a nutritionally incomplete homemade diet or inappropriate dietary supplements leading to excesses of nutrients. Poor cat diets can cause:

  • Diarrhoea or constipation
  • A lack of energy
  • Behavioural problems
  • A dry, dull coat
  • A thin, sparse coat or patchy hair loss
  • Slow fur regrowth
  • Dandruff
  • Pressure sores
  • Vision problems
  • Heart problems

Of course, all of these can be caused by many medical conditions too, so it’s important to have your cat examined by a vet if you notice any of these symptoms. They will check for underlying medical problems and advise on the best diet for your cat if needed.

Other considerations

As tempting as it can be, it’s best not to give human food to your cat, even as a treat. Many human foods are actually poisonous to cats. It could also mean that your cat eats less of their own food, upsetting the nutritional balance of their diet, not to mention causing weight gain!

You should never feed dog food to a cat, since they have very different dietary requirements, and this can be very harmful.

Cats would naturally spend much of their day hunting, which is mentally and physically stimulating. It’s a good idea to try to recreate this natural behaviour in the way you feed, to avoid boredom and to provide stimulation. Feeding little and often and using puzzle or toy feeders can work well.

Frequently Asked Questions about the Best Diet for Cats

Is a high protein diet good for cats?

Cats have higher protein requirements than most domestic animals, including dogs, because they use protein as their primary energy source. Adult cats need a minimum of 26% high-quality protein, and ideally higher. Having enough high-quality protein is especially important for growing kittens and nursing queens.

Elderly cats still have high protein requirements, in order to maintain muscle mass. However, if an elderly cat is suffering with chronic kidney disease (CKD), then they may benefit from a reduced protein diet. For this reason, it’s best to discuss diet with your vet once your cat reaches their elder years (8+).

How can I add fibre to my cat’s diet?

Adequate fibre can be beneficial for gut health, constipation, diarrhoea, and some medical conditions such as diabetes and obesity. You can add fibre to your cat’s diet by feeding a specially formulated high-fibre cat diet, or by adding a fibre supplement designed for cats.

It’s best to avoid adding any ‘human’ foods to increase their fibre, since the amount you would need to add to make a difference would be huge! Always consult your vet before starting your cat on a high-fibre diet, as this is not suitable for all cats.

What is the best diet for indoor cats?

Indoor cats tend to get less exercise than outdoor cats, meaning they can be more prone to putting on weight! You can buy diets specially formulated for indoor cats which have reduced calories, amongst other benefits. Otherwise, ‘light’ diets are a good choice. Exercise is really important for indoor cats too, so it’s a good idea to turn mealtimes into a game and encourage them to ‘hunt’ for their food.

How much to feed a cat on a diet?

To lose weight or maintain a healthy weight, knowing how much to feed a cat on a diet is essential. Your veterinarian can calculate the calorie requirements for your cat, or—once you know your cat’s current weight and body condition score—you can use this calorie calculator. You’ll then need to work out how many grams of food you should be feeding.

Weighing cat food is far more accurate than measuring it with a cup—try sitting down on a Sunday night and weighing out each day’s allowance into tubs rather than weighing it out in the rush of the week.


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