It's called amenorrhea when you lose your period. It's because you drop body fat, but not at all unusual for female athletes.
9 seconds sound clip from the G.I. Jane movie soundboard.
You can hear this line at 00:56:17 in the Blu-ray version of the movie.
Quote context
[...]
- Damn. Is it hot out here, or is it just me?
- This?
- Okay, you can get dressed. Try to get as much air on those abrasions on your back as you can.
- Okay, you got tendinitis in your right knee and that is standard issue jungle rot on your left foot.
- Lovely.
- Let's fix me up and get me back out there.
- Whoa! Ladies! If I follow you home, would you have premarital sex with me?
[...]