We have a spreadsheet that has sensitive data, so we protect all of the sheets so the user can't change anything if they open the file and select to Disable the macros. However when we zip the file, it only goes from 16,478 KB to 15,840 KB. I then went into the file, unprotected all of the sheets, and saved it. I then zipped that file and saw a big change in the size of the file. It went from 16,475 KB to 2,639 KB.
We don't want to keep the sheets unprotected because of the risk of users changing the data, but is there a way to allow them to zip the file to make it much smaller?