How to reduce size of writer document

I have one page document in ODT format that contains A4 size table. Most of table cells contains only text. Around 10 cells contains pictures in .png format. One picture is have size 150x150px and rest of pictures have size 50x19px.

File size of those png files are around 10-20kB. Why writer document size is around 12MB?

Also if I remove all data away from table including all pictures size of writer doc (empty doc) is around 12MB.

I have other writer odt documents that have even bigger pictures and several pages but size of them is around 1MB. Is it table that is causing size issue here? Or is it my way of working. I have created template by adding pictures to table and removing them to find out best fit for table that I am using.

Best regards,
Markus

Which LibO version and which OS?

What happens if you start clean with a new document and instead of embedding the images, you link to them?

Check if you are embedding the font in the file. In File menu, then Properties, then Font tab.