In The Office episode, Lice, Meredith Palmer shaves her head to avoid getting lice.
Here’s how the bald effect was achieved:

(Click the image to see it larger, that’s what she said)
Posted with permission from Edward French. See more at http://edfrenchmakeupfx.com.

Cool to know, but I am kind of disappointed to find out that Kate didn’t actually shave her head.
So, why was she bald in the episode before?