That is exceptionall thin.......she's probably sporting a whole 13% body fat (if she's lucky). My sis used to catwalk model, and believe me, the thing those girls do to keep themselves thin. MY sister was around the same build (179cm and weighed less than 50kgs and she was way into exercising)....she was severely underweight....and told by her manager not to gain any weight. The most thrilling topic in the change rooms was who had the most concave stomach. I can tell you exactly how to get that thin.....don't eat!!!! Oh, yeah throw in some really hard core gym sessions, followed by dizzy spells, emotional discord, depression, a suppressed immune system.
Check out this link. I know its Aussie and all, but at least they are real people, who look fit and healthy, not emanciated fashion slaves.
http://www.sportzblitz.net/body-blitz-c ... r-2004.php
I'm not belittling your choices, and I marvel at your dedication to improve your physique, but I also believe that you should appreciate your uniqueness. I suppose you will be entering the 12 week shape up challenge that Rob has posted?