If all you care about is unformatted text, copy/paste will do that.
Otherwise, as far as I know, you may only paste it as an image, using Adobe
Reader's snapshot tool. Word allows you to paste in many formats, when you
select "Paste Special". Bitmaps and "tiff" files are megabytes in size, but
".png" format ".jpg", Windows Metafile or Enhanced Metafile work best; try
them all to see what works best for your particular situation.