My cat is very slender but has a good appetite. What should I do?

If your cat is eating a lot but is still underweight or losing weight there is likely to be an underlying problem.

Overactive thyroids result in these symptoms and are common amongst older cats. 

Other conditions with similar effects include, but are not limited to, nutritional absorption difficulties, viral infections, and cancer.

To find out the underlying cause it is best to consult a veterinarian and book an appointment for an examination that includes diagnostic testing.