I submit that my answer carries the same meaning, though it was not accepted: "Go now? I have just barely eaten!" It also indicates unwillingness, and acknowledges that "jo" is in the sentence, rather that reading the same as if it wasn't there. Not to say that "jo" is a translation of "just" but it does convey the sense of mild contradiction.
This is true, although 'only just eaten' and 'just eaten' means I've just FINISHED eating and hardly/scarcely/barely eaten means I've just STARTED eating. (For those people who might not have English as their first language.) To use 'just' in this sentence without the hardly/scarcely/barely modifier will always mean finished.