How to Tell If a Cat Is Underweight?

Adult cats average 3.6-6.8 kg; small cats 3.1-4.5 kg, large 5.8-10.8 kg, males heavier. Under 10-20 percent of standard is thin; over 20 percent is emaciated.

A thin cat shows a sunken belly from the side and prominent ribs. Causes include poor nutrition or parasites; feed high-protein food, deworm regularly, and see a vet if weight does not rise.