Why Do Cats Get Fat?

They’re squishy, they’re chonky, they’re adorable – but why do cats get fat? There’s a growing number of fat cats in the world, and on the internet, but what’s at the root of this problem? Studies have varied results, but it’s estimated that anywhere between ~20%-60% of cats are overweight. With so many cats being overweight, we need to know… why do cats get fat in the first place?

Is being fat bad for cats?

Obesity itself is not a ‘death sentence’. You don’t die from being fat. You can, however, be at an increased risk of suffering from other conditions. Increased risk does not mean “will definitely get”.

We all take on additional risks in our lives, even as humans. Did you know that when you’re driving, your risk of dying doubles for every 10 mph (or 16 kilometers) you go over the speed limit? I’m betting every single one of you reading this has either driven a car that was going faster than the speedlimit or been in a car that way. And you’re still here, alive, reading this. Having an increased risk of something happening doesn’t mean that it will happen to you eventually. It just means a higher chance.

Cats that are obese do have a greater chance of developing diabetes, fatty liver disease, teeth and mouth issues, skin problems, and urinary tract problems amongst other conditions. Cats that are obese can also have a decreased quality of life due to joint problems and an inability to groom themselves thoroughly.

Regardless of the fact that there are many overweight cats who are not currently suffering from issues related to their obesity, you can never assume that these issues won’t creep up in the future so it’s best to help get your kitty’s weight under control as soon as you recognize a problem.

So why do cats get fat? Let’s explore…

#1 – Calories in Vs. Calories out

There are many different things that can contribute to why there is a growing feline obesity epidemic, but it’s not all related to just calories in vs. calories out. Yes, any living body (whether it’s a human one or a cat one) can be at a higher risk for gaining weight if they’re eating more calories than their body needs in a day.

Some cats are able to self-regulate and stop eating when they’re satiated. Other cats – like Hercules – will eat until they are uncomfortably full and may even vomit. Free feeding your cat can lead to them gaining weight, especially if they themselves cannot control their appetite and are overeating and you are putting more calories into the bowl than they need in a day.

#2 – Breed

There absolutely are some cat breeds that are larger breeds. Maine Coon cats, for example, can be up to 25 pounds as their normal size. However, there is not a lot of strong evidence that cat breed is associated with the risk of obesity.

When Hercules had his DNA profiled from BasePaws, it showed that the largest percentage of DNA breed in his makeup was Maine Coon. Russian Blue male cats can also be upwards of 15 pounds, as American Shorthairs, and Ragdolls can be up to 20. Herc’s DNA makeup contained a high percentage of cats that were very large breeds. This is why Herc’s goal weight was around 19 pounds (factoring in some loose skin). His body was tall and long in addition to being fat.

Some studies have shown that non-pedigree cats (ie: your standard domestic short/long hairs) cats are at an increased risk of obesity while others say that ginger cats are more likely to be overweight, too.

#3 – Age

Why do cats get fat when they age? This is because older cats become less active, especially when they are indoor cats. Aside from activity levels, older cats often require fewer calories as metabolism changes throughout life. This means that an older cat can be more likely to put on extra pounds than a younger cat.

#4 – Sex

Male cats are at a higher risk of obesity than female cats, especially male cats that are neutered.

#5 – Neutering/Spaying

When a cat is neutered or spayed, its metabolism slows down. By how much? It seems to vary from cat to cat, but enough that without a change in diet, the risk of weight gain is real. Of all the reasons why cats get fat, neutering and spaying seem to be the most common cause.

#6 – Medical Problems

Why do cats get fat is they have medical problems? A lot of people assume that when a cat has a medical problem it will lose weight, and while this can be very commonly seen in conditions like kidey disease or diabetes, a cat that is gaining weight without a change in diet can also signify a potential health problem.

Weight gain can be due to fluid retention, not necessarily fat deposition. Heart disease, FIP, and other abdominal tumors can cause fluid retention. Acromegaly is a hormonal condition where the cat generates too much growth hormone, due to a problem with the pituitary gland. A cat can also have too little thyroid hormone, called hypothyroidism, that can cause obesity. Cushing’s disease is another hormonal problem that can be seen in cats; with Cushing’s, the cat has too much cortisol and this can cause weight gain amongst other symptoms. Arthritis and pregnancy can also be associated with weight gain, but indirectly as contributory factors rather than causal ones.

#7 – Quality of food

Low-quality food means food that isn’t directly benefiting the cat from a nutritional standpoint. This can mean food that contains a lot of carbohydrates and other fillers, food that contains too much fat, or even table scraps and various human food. (Do not assume that carbohydrates are bad for cats. While cats are obligate carnivores, they do have complex nutritional needs and they are no longer ‘wild animals’. They have been domesticated and through that process, nutritional needs have also changed. We recommend WSAVA approved diets for cats and not raw diets)

#8 – Lack of exercise

As your cat moves less, they will require fewer calories. While a cat won’t lose their weight with exercise alone, getting them moving – even a bit – can help with weight loss.

Unfortunately exercising a cat can be increasingly difficult relative to how large the cat is as well as how old the cat is. Hydrotherapy at home in your tub is always an option:

Spicy language warning in the video below

@ten2tenphotography Things in my fat cat adapted household – PART 4 #fatcat #chonky #plussizeedition #curvy #petstory #catslovers #wapchallenge #hydrotherapy ♬ original sound – Erika Kathryn

#9 – Owner’s perception of their cat’s size

Studies show that many owners have a difficult time assessing their cat’s body condition; often assuming that a cat is not overweight when in fact they are. This can be for a number of reasons including what’s shown in the media but also due to a lack of education around what a cat body should look like at an ideal weight.

#10 – Medication side effects

Certain medications, like steroids, cause weight gain even if the cat is not eating a surplus of calories. There are many times when a vet team is faced with situations where they have to balance multiple issues and choose to administer medication that can cause weight gain because the benefits of treating the underlying issue outweigh any additional risk that weight gain may cause.

So why do cats get fat?

There is no single reason why cats get fat, and often it is due to a variety of reasons. While some reasons are more common than others, it’s important that we recognize that feline obesity is an important issue to address but also that is can be a complex issue that isn’t just about “evil owners overfeeding their cats”. Understanding why cats get fat means putting aside your own biases and anti-fat attitudes and looking at the big picture of what’s going on in the cat and the owners life.