Weight loss in cats can be concerning, especially when it happens unexpectedly. While some weight changes can be normal, rapid or unexplained weight loss often signals an underlying issue.
As a veterinarian and cat mom, I know how important it is to keep an eye on your cat’s weight and recognize when a trip to the vet is necessary. In this article, we’ll go over what a healthy cat weight looks like, potential reasons for weight loss, and how to help your cat regain a healthy weight.
How much should a cat weigh?
A healthy cat’s weight varies based on breed, age, and body type. In general:
- Most domestic cats should weigh between 8-12 pounds.
- Larger breeds like Maine Coons can weigh 15-20 pounds.
- Smaller breeds like Siamese cats may be healthy at 6-8 pounds.
Rather than focusing solely on numbers, evaluating body condition score (BCS) is key. A healthy cat weight can be recognized by a visible waistline, easily felt ribs without excess fat, and a slight abdominal tuck when viewed from the side.
How to weigh your cat
Regular weight checks can help detect gradual changes before they become serious. Here’s how to weigh your cat at home:
- Use a digital scale for accuracy.
- Weigh yourself first, then weigh yourself while holding your cat.
- Subtract your weight from the combined weight to get your cat’s weight.
- Keep track of changes over time.
Alternatively, if you have the Litter-Robot 4 self-cleaning litter box, you can track your cat’s weight through the connected Whisker app every time they use the bathroom. Easily view weekly and monthly charts to gauge if your cat’s weight is fluctuating.
For the most precise measurements, you can visit your vet for regular weigh-ins.
How much to feed a cat
- Indoor adult cats: 20 calories per pound per day
- Active/outdoor cats: 25-30 calories per pound per day
- Senior cats: Caloric needs may decrease, but weight loss should still be monitored
Check the feeding guide on your cat food packaging and adjust as needed.
Why is my cat losing weight?
There are several reasons your cat may be losing weight, ranging from simple diet issues to serious medical conditions. Let’s dive into cat weight loss causes.
Not getting enough food
Here are a few reasons why your cat may not be getting enough food:
- Portion sizes too small
- Competition with other pets for food
- Low-quality food lacking essential nutrients
- Changes in appetite due to stress or environment
Health-related issues
Weight loss can be a symptom of various illnesses, including:
- Hyperthyroidism – Increased metabolism causes weight loss despite a strong appetite.
- Diabetes – Cats may lose weight while eating more due to improper glucose regulation.
- Kidney disease – Loss of muscle mass is common in cats with declining kidney function.
- Cancer – Tumors can cause weight loss even when appetite seems normal.
- Gastrointestinal disorders – Inflammatory bowel disease (IBD) or food allergies can interfere with nutrient absorption.
- Dental disease – Painful teeth or gums may lead to decreased food intake.
Serious diseases
Some of the more serious conditions linked to significant weight loss in cats include:
- Feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV), both of which weaken the immune system and can lead to chronic infections and muscle wasting.
- Intestinal cancers, such as lymphoma, can cause progressive weight loss and digestive disturbances.
- Liver disease, particularly hepatic lipidosis (fatty liver disease), can lead to rapid weight loss and dangerous complications if untreated.
- Advanced heart disease can also result in muscle wasting due to reduced circulation and metabolic stress. Identifying these conditions early through veterinary diagnostics is essential for effective management.
Cat losing weight but acting normal
If your cat is losing weight but still eating, drinking, and behaving normally, it could indicate:
- Hyperthyroidism (common in older cats)
- Early kidney disease
- Diabetes
- Parasites
- Malabsorption issues (not absorbing nutrients properly)
Since these conditions may not show immediate symptoms beyond weight loss, routine bloodwork is often needed to identify the cause.
When to take your cat to the vet
If your cat has lost more than 10% of their body weight without explanation, it’s time for a vet visit.
Additional symptoms to watch out for
If your cat is losing weight, also look for:
- Increased thirst or urination
- Vomiting or diarrhea
- Lethargy or hiding
- Changes in coat quality (dull, greasy, or patchy fur)
- Bad breath (could indicate kidney or dental disease)
- Decreased muscle tone
These symptoms, combined with weight loss, may indicate an underlying medical issue requiring veterinary attention.
Your veterinarian may recommend:
- Bloodwork to check for thyroid issues, diabetes, or kidney disease
- Urinalysis to assess kidney function and hydration levels
- Fecal tests for parasites
- X-rays or ultrasound if a mass or GI issue is suspected
- Dietary review to ensure your cat is getting enough nutrients
Older cats losing weight
Senior cats often experience weight loss due to age-related muscle loss (sarcopenia), but it should not be ignored. Common causes include:
- Chronic kidney disease
- Hyperthyroidism
- Arthritis pain affecting mobility and appetite
- Cancer
- Dental issues
Regular vet check-ups can help identify why your cat is losing weight and manage these conditions early.
How to help your cat gain weight
If your cat is underweight, these strategies can help:
- Switch to a calorie-dense diet: Veterinary prescription diets or high-calorie wet foods
- Offer smaller, more frequent meals throughout the day
- Use warming techniques: Warm food slightly to enhance aroma and encourage eating
- Provide a stress-free eating environment to reduce anxiety-related food avoidance
- Add high-calorie toppers like canned pumpkin, cooked egg, or veterinary supplements
- Address the underlying issue with your veterinarian
Appetite stimulants for cats
If your cat is reluctant to eat, your veterinarian may prescribe:
- Mirtazapine – A common appetite stimulant for cats
- Capromorelin (Entyce/Elura) – Mimics hunger hormones
- Steroids – Occasionally used for appetite stimulation in chronic conditions, though less common
Always consult a vet before using any medication.
Final thoughts
Weight loss in cats can be a sign of anything from simple underfeeding to serious illness. Regular weight monitoring, a well-balanced diet, and early veterinary intervention can help ensure your cat stays healthy. If you’re unsure why your cat is losing weight, a trip to the vet is the best way to rule out any medical concerns and create a plan to restore their health.
