My adult hasn't been eating, (I'm goin to be deworming him this week) and I was holding him this morning...

I'm not at all concerned yet, but I was feeling him I felt how his skin was loose-ish... Obviously that's normal, but as paranoid as I am right now it made me paranoid. How loose it too loose? I dot ever remember it being this loose... but again that's me being paranoid. How loose is too loose? How would I know? Why would it mean?