I only lose weight on Friday and Saturdays!!!! WHAT GIVES!!!!!!!

Hi all!

I'm having this issue in the last few months where my body gains about 2-3 lbs sun-thurs, and then on Friday and Saturday I usually drop about 5 LBS or so!!! I know i'm losing and that is awesome!!!  But what gives with this strange pattern?? Anyone else experience anything like this?

I only weigh once a week.  Same day, same time.  Saves a lot of frustration!