How can a Microsoft Word document reduce size?

Most of the size of a Word document is bloated formatting settings, not the text itself. Did you reduce the amount of formatting as well, when you added the extra text? Run some paragraphs together that used to be separate?

Thanks for the speedy reply but the formatting has not changed at all. I checked the word/paragraph count and that went up as expected so I don’t seem to have lost anything.

@flutherother that is strange then. I can’t think of anything else.

Word 2007 stores files as .docx by default. This is a file type uses ZIP compression to reduce file size so the file size may vary on a day to day basis depending on how well ZIP can compress the data. If everything is still there in the file then I wouldn’t worry about it too much.

OK, well that’s reassuring. Thanks.

It probably uses some compression. Compression looks for patterns to encode so adding text might have created an extra pattern. (A bit of a guess).