I don't mean to sound mean, but are you trying to use this forum to help you lose weight, or do you have an ed? This forum is for people to provide support to each other with their struggles. It is not a forum to encourage you to lose weights. Starving is always bad, and yes it can mess up your menstrual cycle. Whether that me anorexia, bulimia or any other ed.
I'm sorry to sound harsh, but coming from someone who has suffered the trials and tribulations with the ed and recovery, I now know that the behaviour is not the answer. As moya hornbacher said "it's ever so easy to go, harder to find your way back". No one has ever said anything truer.