Does your cat’s big fat belly appear to comedically swing from side to side when it walks or runs? You might just be looking at its primordial pouch, which, despite looking completely ridiculous, provides your feisty feline with a complex evolutionary advantage.

All cats – male or female, neutered or intact – have a primordial pouch, and while they may appear larger in overweight cats, they are not usually a sign that your cat is fat. Even big cats like lions have primordial pouches, and they differ in size between each individual.

A cat’s pouch will form when they’re around six months old, and while obesity, pregnancy and aging may change the appearance of its pouch, you’ll know pretty early on if your cat’s got that swing in its step. However, if you notice any sudden changes in the shape of your cat’s body once fully grown, it could be a sign of a health condition so it’s always best to get it checked with a vet first before pointing and laughing.

While primordial pouches might make your cat look like a floppy idiot, they may actually be serving some pretty badass purposes:

• Protection: famous for their “bunny kicking” abilities, these pouches provide an extra layer of fat and tissue to protect the cat’s vital organs from sharp claws during fights and playful roughhousing. 
• Flexibility: cats are able to extend their bodies to perform impressive jumps of distances approximately five to six times the length of their body, both vertically and horizontally. This extra skin allows them to take longer strides, leap further, and twist their torso to land on their feet.
• Food storage: while domesticated cats tend to prefer their food little and often, many breeds haven’t physically evolved far from their days as wildcats. In the wild, cats may gorge on a large meal when food supplies are limited, and these pouches allow their bellies to expand to accommodate these larger meals.
• Heat regulation: some also speculate that the pouches enable better air circulation that aids in temperature control; however, these are all still theories as experts remain unsure of the true purpose of the pouch.

A common misconception is that only neutered cats develop a primordial pouch, but if you’re seeing a drastic difference in pouch size before and after neutering, your cat is probably just overweight. After a cat is neutered, their decreased energy levels mean they need less food. Owners that continue them on the same diet are likely to see their weight increase, and with that comes an even heftier pouch.

Some breeds, like the hairless sphinx, have more visible pouches, while fluffier breeds keep their flaps better hidden. The International Cat Association, a genetic registry of cats that upholds breed standards much like the UK’s Kennel Club, even have big flappy primordial pouches as a breed expectation for some cats like the pixiebob – a breed that is also praised for having virtually no tail and extra toes (called polydactylism).

Just like in humans, gravity also works its wonders on the primordial pouch, with older cats sporting more saggy, elongated pouches. A good way to check if your cat is the proud owner of a big pouch or just a fatty is to give it a squeeze.

Primordial pouches are only present on the underside of the belly and are soft and floppy, while fat deposits are distributed around the body and feel firm or squishy to the touch. So go ahead and give your cat’s primordial pouch a jiggle, for health reasons.