Database backup file size is too small compare to actual database size

Hi All,

I know that backup file size can be smaller than actual DB size (i.e., MDF size + LDF size). But in my case i am observing huge difference. 

My Database size is 16 GB out of which 10 GB consumed by MDF and 6 GB consumed by LDF. But when i took the backup, the backup file size is only 1 GB!!!!!

I am skeptical about whether i am doing anything wrong. Please advice me.