Large ODT file bloats when stored to 4 x its size

I have a large ODT file of some 194Mb. I made a very small text edit but when closed it had bloated to 4 x its original size, Consequently it takes ages to open and close. The word count is still the same & correct. There are several photographs involved in this admittedly very large document 194Mb now 768Mb
Can you help me to get this back to its rightful size. I will then archive it for read only use. I have created a new document for its continuation as its a diary of sorts.
Thanking you in anticipation
Best regards
BerryG

Edit @Hrbrgr: Unnecessary font formatting removed.

Please add the information about your OS and Version, Menu/Help/About LibreOffice.

Does it have enable track changes?