Show only changed lines without syntax with git diff

I have a list of usernames that are in a text file. I update this file and commit it. I am looking for a way to get a list of the changes since the last commit. I do not want any diff formatting at all, I just want to get an output that has usernames one per line (as they are added to each commit) since the last commit. I can't find a setting that will remove all the git diff syntax from the output so it's purely a list new lines added only. # Example Original file: user1 user2 user3 I then add user4 user5 Then commit. I want to be able to do a git diff and see only: user4 user5