As we all know, cats have very sensitive stomachs. That makes me wonder. Once a cat gets used to a specific food, are they used to it for a lifetime? To make an example:

I feed my cat Food A for a year. Then I slowly transition to food B, and feed that for 4 years. If I want to go back to food A now, is it necessary to transition slowly again, just as if it were a new food? Or are their stomachs still "used" to it, so it can be fed straight away (or transitioned much faster)?



1 Answer 1


It’s not that cats’ stomachs are sensitive per se. It’s that the bacteria population in their intestines naturally adapts to their diet, and if you introduce a new food they’re not ready for, it will usually result in diarrhea. This is only really a problem with pets that eat the same food at every meal, and it can be solved by slowly changing their diet to give the bacteria time to adapt.

Notably, while the types of bacteria that can digest the new food are rapidly multiplying, the types that can digest the old food will be starving to death. The cat can’t retain its ability to digest the food you gave it several years ago because those bacteria are all long dead now.

A cat used to a more varied diet (such as a stray or feral cat) will naturally have a more diverse population of bacteria that can easily handle whatever food the cat happens to find for each meal. None of the different types of bacteria ever die out because they all occasionally get food they can digest.

  • Thanks for the detailed response. This makes me realize that it probably is better to feed a variety of food in the long run, just in case you need to switch at some point because of a medical problem. I guess chances will be higher that the cat has already developed bacteria to digest it. Do you happen to know how long it takes for these bacteria to die, when they don't get "their food"? Or in other words, how long is a cat used to a specific type of food? To make an example: I bought a kitten 3 weeks ago. I wonder if she is still used to the dry food she got before i bought her. Thanks Nov 26, 2020 at 8:37
  • @SomeNewKittenOwner It only takes a week or so to change foods, so I’d guess around the same time for not being able to digest the older food, but I wouldn’t be too concerned about it. I do give my cats two dry foods plus a wet, but more to keep things interesting for them than for digestive reasons.
    – StephenS
    Nov 26, 2020 at 14:26

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