File Becomes Huge When I Add Pictures

Hi, we're working with a file in Excel where we are having people insert pictures into the spreadsheet. The spreadsheet with no pictures is 2.3 MB. The picture is 730 KB. But when it is inserted into the worksheet the file becomes 24 MB. If I add the picture again it goes up to 45.8 MB. We used the compree picture option on the toolbar but that only took it down to 23.9 MB for a file with a single picture. We need to E-Mail the worksheet but we can't E-Mail anything larger than 22 MB. Why is it doing this and how can we make the file smaller?