Why Is My Cat Losing Weight?

Cats are small, so even a little weight loss can be significant. A cat that has lost a pound may have lost 10% or more of their body weight. Unexplained weight loss is one of the most important early signs of illness in cats, especially seniors. If your cat is losing weight, it’s worth finding out why.

Is it really weight loss?

Cats’ fur can hide weight changes. Signs your cat may be losing weight include:

• Ribs, spine or hip bones that feel more prominent
• A smaller belly or waist
• Loose skin or less muscle along the back
• A lower number on the scale

Weighing your cat at home every month is one of the easiest ways to catch changes early. Step on a scale holding your cat, then subtract your own weight.

Why is my cat losing weight but still eating?

Some conditions make cats lose weight even when they eat well or seem hungrier than usual:

• Hyperthyroidism, an overactive thyroid that speeds up metabolism. It’s very common in older cats
• Diabetes, where the body can’t use sugar properly. Cats often drink and pee more
• Intestinal disease, like inflammatory bowel disease or intestinal lymphoma, which affects absorption
• Parasites, such as worms
• Exocrine pancreatic insufficiency, a rare digestive enzyme problem

Weight loss with a poor appetite

If your cat is eating less, weight loss may be linked to:

• Dental disease or mouth pain
• Chronic kidney disease
• Cancer
• Liver disease
• Nausea from many conditions
• Stress, like a new pet or a move
• Competition for food in multi-cat homes

Our articles on my cat is hiding and not eating and whether your cat is drinking enough water explain related signs.

Why not eating is risky for cats

Cats that don’t eat for more than a day or two can develop fatty liver disease (hepatic lipidosis), a serious condition. Don’t wait if your cat stops eating.

When to see a vet

Book a vet visit if your cat:

• Has lost weight without a diet plan
• Is eating more but still losing weight
• Is drinking or peeing more
• Has vomiting, diarrhea or changes in stool
• Has a messy coat or less grooming

Go sooner if your cat stops eating, is very lethargic or is vomiting repeatedly. Our guide to pet emergency signs explains other urgent symptoms.

How do vets find the cause?

Your vet may recommend:

• A physical exam, including the mouth and thyroid area
• Blood tests and a urinalysis
• A thyroid test
• Fecal tests for parasites
• X-rays or an ultrasound

Our article on understanding your pet’s blood work results explains common tests.

Supporting your cat at home

• Weigh your cat monthly and keep a record
• Feed in a quiet place, away from other pets
• Offer wet food, which may be more appealing
• Follow your vet’s treatment plan for any underlying condition

Frequently asked questions

How much weight loss is concerning in a cat?

Any unplanned weight loss is worth checking, especially 5% or more of body weight.

Can old age alone cause weight loss?

Some muscle loss happens with age, but weight loss often has a treatable cause.

Concerned about your cat’s weight? Ask a vet

Talk to a licensed vet 24/7, even on holidays, by chat, voice call or video call. Your first month is free with code FREEMONTH, then US $9.99/month, at NYPTeleVet.com. One membership covers up to 6 pets, and you can cancel anytime.

Our vets can’t prescribe medication, but they’ll tell you what’s likely needed and when an in-person visit is the next step.

Sources

• Why Is My Cat Losing Weight? Weight Loss in Cats, PetMD
• Testing for Weight Loss in Cats, VCA Animal Hospitals
• The Special Needs of the Senior Cat, Cornell Feline Health Center