How can I tell if Chico is underweight? For some reason I'm thinking he is because he just looks really skinny when he walks. I leave food out for him 24/7, so it's not like he's not eating, because he is. I'm just confused because I can see the outline of his ribs. When I took him to the vet last month, they said he weighed 8 pounds and is healthy. Does anyone else's smooth coat look like that? Should I have him on a "fattening" food?