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Why is my senior cat eating so much but not gaining weight?

Updated On September 23rd, 2025

Pet's info: Cat | Domestic Shorthair | Male | neutered | 9 lbs

I have 4 cats all 18 years old. One was a stray I've had for more than 19 years. He is painfully thin. They are all neutered or spayed and the others are all normal if not slightly overweight. The thin guy eats a great deal more than the others, but doesn't gain weight.

2 Answers

Most Helpful Answer

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Answered By Dr. Melanie, BVSc MS

Veterinarian

Published on October 1st, 2018

In senior cats who eat but don't gain weight, there are three common conditions that could be causing it: Diabetes, hyperthyroidism, and kidney failure. It could also be caused by cancer. Amigo needs to see a vet, and I would take him into one today. I recommend getting a geriatric blood panel and urinalysis, which can test for those three diseases I mentioned above. If cancer is suspected, that will require more testing. Once a diagnosis is reached, the vet can discuss treatment options with you. Best of luck.

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    Answered By Dr. Melanie, BVSc MS

    Veterinarian

    Published on November 26th, 2017

    In senior cats like Shauni, there can be a medical reason behind why she is not gaining weight and throwing up. There are three common diseases in older cats that cause these symptoms: Diabetes, hyperthyroidism, and kidney failure. I would have her seen by the vet for a physical exam, geriatric blood panel, and urinalysis. These tests will help the vet diagnose if she does have a medical cause behind her being so skinny, and can discuss ways to treat it. I would take her into the vet on Monday or Tuesday. Good luck, I hope this helps!

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