Adult cats will generally die if they don't eat for 5 to 7 days, while kittens will die even faster. This is because cats don't have any substances in their bodies that can help them maintain their health. Therefore, if the owner is going on a business trip and can't take the cat with them, it's best to leave it with a friend for them to take care of. 
If a cat doesn't eat or drink for 24 hours, it will become lethargic and unwilling to move. If it goes more than 48 hours without eating or drinking, it will become sluggish, unable to stand, and may vomit. It is recommended to take the cat to a veterinary hospital for treatment as soon as possible.
A cat's refusal to eat could be due to illness or digestive issues. It could also be caused by indigestion from eating something difficult to digest. In such cases, owners can give the cat probiotics to help restore its digestive function.
