Changing your cat's food too fast can cause vomiting, loose stools or a cat that refuses to eat. A slow, gradual switch is gentler on the stomach and gives a fussy cat time to adjust.
How long should it take?
Plan on at least 7 to 10 days. Catster notes that finicky eaters or cats with digestive problems may need longer, and in rare cases up to a month. Slower is almost never a problem.
A simple transition plan
Mix the new food into the old at every meal, increasing the new food step by step. Here is an example over 10 days:
| Days | Old food | New food |
|---|---|---|
| 1 to 3 | 75% | 25% |
| 4 to 6 | 50% | 50% |
| 7 to 9 | 25% | 75% |
| 10 onward | 0% | 100% |
For a sensitive cat, go slower. Start with just 5 to 10% new food and increase by 5 to 10% every other day, as Catster suggests. Keep fresh water available throughout. Moving from dry to wet food may lower the water your cat drinks, while moving from wet to dry may raise it.
What to watch during the switch
- Appetite
- Litter box habits: how often and how long, and any constipation or diarrhoea
- Vomiting, retching or regurgitating after meals
- Excess shedding or over-grooming (grooming right after a meal is normal)
When to stop
If your cat has vomiting, runny stools, or stops eating entirely, pause the transition and call your vet. A cat that suddenly refuses food and has never done so before should be seen promptly, because it can signal an underlying medical problem. Catster warns that going without food for more than 24 to 48 hours can lead to fatty liver disease, which needs urgent veterinary care.
If your cat refuses the new food
- Try a different food. Cats can be picky, and a different flavour or texture may work.
- A food topper can tempt a cat, but it adds calories and cost.
- For kittens that do not yet recognise a food, put a small amount just under the nose so they lick it.
- Remember the difference between "not hungry" and "doesn't like it". A cat that is not hungry may be unwell.
Special cases
- Kitten to adult food: usually at about 10 to 12 months, using the same gradual plan. See kitten feeding schedule.
- Adult to senior or prescription diets: talk to your vet first. See senior cat diet.
- Dry to wet: follow the same steps and measure calories carefully. See wet vs dry cat food and how much to feed a cat.
- Weight loss diets: never put a cat on a crash diet. See healthy cat weight.
For the complete overview, read the cat feeding guide.
Frequently asked questions
How long does it take to switch cat food?
At least 7 to 10 days. Longer is fine for sensitive or picky cats.
Can I switch my cat's food cold turkey?
It is not recommended. A sudden change can upset the stomach and make a cat refuse the new food.
Why is my cat not eating the new food?
It may simply not like it, or it may be unwell. If your cat refuses all food, see a vet. If it only refuses the new food, slow down or try a different one.
Is it normal for a cat to have loose stools when changing food?
Mild changes can happen, but vomiting, runny stools or stopping eating mean you should pause and contact your vet.
This article is general information, not veterinary advice. Talk to your vet before changing your cat's diet.