Feline Fatty Liver Disease: Hepatic Lipidosis

Rapid weight loss isn't healthy for humans, and it's no good for kitties either. Here's why: When a cat stops eating and quickly loses a lot of weight, it can lead to an overaccumulation of fat in the liver, called feline fatty liver disease, or hepatic lipidosis (HL). Untreated, HL can result in permanent liver damage or liver failure.
So if your cat stops eating for more than a day or two, take her to the vet promptly. Other symptoms to look out for include:

Lethargy
Dehydration
Vomiting
Diarrhea or constipation
Excessive salivation
Jaundice (yellowing skin, eyes, or gums)
Ask your vet about blood work (to check liver function), urinalysis, and other tests to rule out any underlying diseases that may be causing the weight loss. It's important to get your cat eating again. Treatment may include:

Medications to stimulate appetite
A special diet to help with liver function
Subcutaneous fluid therapy to combat dehydration
Temporary use of a feeding tube
Vitamin, mineral, and/or amino acid supplements
All cats can get HL, but overweight and obese cats are especially vulnerable. So if your pet is overweight, talk to your vet about a safe and healthy weight loss diet for your kitty. Learn how to prevent excess weight gain to begin with.