Rasputin, you'll know when you get closer to goal whether it's unhealthy or not. It doesn't sound unreasonable for your height and size... Don't sell yourself short and think, "oh, I could never get to the size I really want to because I'm so far off" When you get closer you may realize that your bodyfat will be 20% at say, 135 pounds OR it could be 20% at 115 lbs. It depends on the type of training you do from now until then and how much muscle you carry.......I have people telling me all the time that to lose 5-10 lbs is unreasonable, it's unhealthy for me to want to have less bodyfat. WHATEVER. They're all people who are sedentary and don't really put any effort into their physical health. 120 lbs doesn't sound unhealthy FOR NOW, just wait until your closer and you'll know for sure. Don't doubt yourself.

Meg