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Why is my cat so thin and how can I help him gain healthy weight?

Updated On September 23rd, 2025

Pet's info: Cat | Domestic Longhair | Male | neutered | 6 years old

My 6 year old cat seems too thin. I can feel his spine, ribs, and hips quite easily. Last year I mentioned this to his vet and he agreed that he was a bit thin. On a body composition of 1 to 9 Choo Choo was a 4. He wasn't overly concerned at the time. Choo hasn't got any fat on him. What causes this? Should I be concerned? How can I put some fat/weight on his bones (only a little because too much isn't good)?

2 Answers

Most Helpful Answer

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Answered By Dr. Elizabeth

Veterinarian

Published on April 28th, 2019

Cats can be thin for a variety of reasons. Make sure he has been checked for parasites or dewormed recently. Some cats will also become thin due to kidney disease or hyperthyroidism. Sometimes this can happen even before kidney disease begins. Any GI disease will also cause a thin body. Lastly, some cats have a fast metabolism. Make sure Choo Choo's bloodwork is all normal and that parasites are not a concern. Then you may try focusing on nutrition. I recommend the brand Royal Canin. It's diets are all tested and formulated to contain appropriate protein levels that are high quality and easy to digest. Feed one of the higher calorie diets available. This may help to put weight on him. You can also supplement with a high calorie canned like A/D or R/S.

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    Answered By Sarah Box, BVSc

    Veterinarian

    Published on April 27th, 2019

    Poor Choo Choo. I am sorry to hear he is having weight difficulties. I would strongly recommend that you take him in to your regular veterinarian for a thorough physical examination and some bloodwork. They can check for things like kidney disease and hyperthyroidism that can lead to excessive weight loss. Cardiac disease, dental disease and cancer can also be disease processes that could cause weight loss. If your veterinarian does not find any evidence of disease, they may recommend some diet changes to encourage extra calorie intake. I hope Choo Choo feels better soon.

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