Why a 6 kg cat might handle this differently than a kitten
An adult cat weighing 6 kg has more body mass to process small amounts of butter and salt compared to a tiny kitten. The few cooked kohlrabi pieces themselves are fibrous but not toxic, and their soft texture from cooking makes them easier to digest. However, even this modest portion contains enough fat and sodium to potentially irritate a cat's sensitive digestive tract, especially if they rarely eat human food.
The butter's high fat content could trigger temporary pancreatitis in susceptible cats, though this is less likely with such a small quantity. The salt may cause noticeable thirst increases or mild electrolyte imbalance if your cat isn't drinking enough water to compensate. Neither component is immediately dangerous at this dose, but together they create more stomach upset risk than plain vegetables would.
What to watch for in the next 12 hours
Monitor your cat for subtle changes like excessive lip-licking or repeated swallowing, which often precede vomiting. Diarrhea may appear within 6-8 hours if the fat content overwhelms their system, possibly with greasy-looking stool. Increased water consumption is expected due to the salt, but frantic drinking or urinating much more than usual warrants concern.
Lethargy lasting beyond a brief post-meal nap suggests their body is struggling with the rich food. While most cats will process this without issues, those with pre-existing conditions like inflammatory bowel disease may react more strongly. Any vomiting that persists beyond two episodes or contains bile (yellow foam) means their stomach needs professional support.
How the preparation method changes the risk
Boiled or steamed kohlrabi retains moisture without adding oils, but your version likely absorbed butter during cooking. That fat coats the vegetable fibers, making them slide through the gut faster than raw pieces would. The salt probably stuck to the kohlrabi's porous cooked surface rather than being evenly distributed, creating tiny salt-dense spots your cat ingested.
The cooking process broke down some of kohlrabi's tougher cell walls, releasing compounds that might mildly stimulate digestion. This isn't harmful, but combined with the butter's laxative effect, it could explain loose stools later. Had the pieces been fried instead of lightly cooked, the higher fat concentration would pose greater pancreatitis risk even in this small amount.
When to offer their next meal
Wait at least 4-6 hours before providing their regular cat food to let their stomach settle. If they seem hungry sooner, offer a tablespoon of plain boiled chicken (no skin or seasoning) to buffer the fat absorption. Their usual water should always be available to help flush the extra sodium, but don't force them to drink.
Skip treats for 24 hours to monitor how their system handles this unusual meal. Future veggie treats should be raw (peeled) or steamed without additives—cats lack taste receptors for sweetness, so they don't need seasoning. One episode of soft stool doesn't require intervention, but multiple watery bowel movements mean their gut needs a bland diet and possibly vet-recommended probiotics.
The full verdict, portion guidance and serving notes are collected on the Kohlrabi food facts page.