I've had 6+ cats over the years. One was quite thin as a 1 year old, the vet said he was the "ideal cat weight" even if he felt a bit skinny to us. As a 6 year old, that cat is now long and lean, feels just right. Our other cat though, approaching two, is a whole other thing. She is happy and healthy, but I suspect she qualifies as just a bit clinically underweight. Always been that way. I say suspect because she is a medium hair cat, and it isn't so easy to compare her to the online illustrations. They have dry or moist food available most of the day and night, she just doesn't eat that much. Now we don't take cats to the vet absent a problem, you can judge that if you like, but in any event, she hasn't been since she was a kitten. I don't think its a real health issue in any event, as she is behaviorally normal in all respects, and actually weighs considerably more than one would expect from feeling her body shape. So I'm thinking I'd like to do some special feedings of a higher calorie food for her only. Any suggestions?