Regarding Excel file size issue while attaching it with email from ABAP

Hi Guys

I am sending an excel file as a mail attachment using background scheduled program in ABAP. This is working fine .

After I downloaded the excel file from the mail (Fileone.XLSX ) its size is 10 MB ,I Just open this file and copying the full data and pasting it in a new excel sheet separately and saving it as excel in local folder( Filetwo.XLSX) the size of the excel file is very less ( app 150 KB ) when I compare with the fileone .

Why this is happening? How can I avoid this size issue ?

Please suggest .Thanks in advance .