There are hundreds of thousands of workout videos on YouTube.  However, there's just one that I'm aware of where you see someone drop weight this fast.

A fitness website called TheDailyHIIT.com shows an insanely in-shape woman doing some kind of crazy workout. Not as strange as the Shake-Weight, but I digress.  In the background of this video, it's not hard to see a bathroom with its door open, and some guy sitting on the toilet.