Why won't my cat eat food but only treats and is losing weight?

These are indeed an unusual set of symptoms, thyroid disease and diabetes would be the first suspects for a cat with increasing appetite and weight loss. A specialist ultrasound scan of the abdomen may be worth while to investigate difficulties with food digestion and absorption or even tumours using up the calories

Appetite changes and weight loss in older cats are usually due to an underlying medical problem, rather than just "getting old." Some common possibilities would include chronic kidney or liver disease, diabetes, or dental problems. Many of these issues are very treatable once a diagnosis is made, so I would recommend taking Poppy to the vet for an exam when you are able to. He/she can do blood work to help diagnose the problem and get her started on appropriate treatment.

If thyroid levels are in normal range then the most common differential diagnosis is Lymphoma which is a type of cancer, unfortunately it is more difficult to diagnose, an experienced ultrasound specialist vet will be able to confirm or rule it out.

Cats get hyperthyroidism and this actually causes them to get too skinny. Cats who are over weight at at a much greater risk for diabetes but if they get the disease, they tend to lose weight and drink excessively. To answer your questions though, both conditions require blood work for diagnosis. Most cats get heavy because they eat too much and their metabolism slows down. Feeding multiple cats is difficult when one needs to lose weight and requires commitment on the humans part. You cannot leave food down all the time. You must separate the cats at feeding time. You must switch the heavy cat to a light cat food and control the portions. Cats do best if they are feed 4-6 times a day. For my own fat cat, I got an automatic feeder that stays shut in a room. It portion controls and is timed. All I do is open the door and shut it behind him. It’s pretty easy and I like that. I hope this is helpful and please feel free to post any additional questions.

With the symptoms you are describing I tend to test for advanced kidney disease or hyperthyroidism. I would encourage him to eat as best you can and get him to a veterinarian. With blood work and a urinalysis they should be able to give you a diagnosis and help direct you as to what is next

In an older cat, my first thought would be dental disease. This would be painful for Krinkle, cause him to eat less, and subsequent weight loss. It could also be that he has diabetes, kidney failure, or hyperthyroidism. Having him seen by a vet this week is a good idea. I hope this helps!

Poor Sachi! Significant weight loss and inappetence are certainly a major concern. I'm glad to hear that his blood work (I assume a CBC, chemistry and T4?) was unremarkable. However, foreign body intestinal obstruction/blockages, intestinal malabsorption issues that can cause inflammatory bowel disease (IBD) or exocrine pancreatic insufficiency (EPI), chronic pancreatitis, or cancerous processes, do not necessarily cause changes on screening blood tests. If Sachi has not yet had abdominal x-rays or an ultrasound, consider talking to your vet about these tests as his next diagnostic step. If he has a foreign body obstructing his intestines, this is a surgical emergency, and these tests would be helpful in obtaining a diagnosis. If pancreatitis, IBD or EPI are more highly suspected, consider talking to your vet about testing for vitamins B12 and folate, as well as TLI and fPLI. I hope this helps!