Brief male and female butt nudity in both seasons.
The females on the show wear workout shorts and sports bra tops when they wake up.
There are several "sex" scenes that don't show nudity, but have hard breathing, grinding, etc. One of these scenes is a three-way between one girl and two guys kissing. This is very heavy, but doesn't show any nudity.
There is no male or female frontal nudity.
Two scenes where Katee Sackhoff is shown with her hand in her pants, presumably masturbating. Action itself is not shown but is heavily implied.