Twinklestar, you are already very underweight. I don't know how old you are or how tall, but in general a BMI of 20 or under is considered underweight, and 17.5 and under is one of the criteria for anorexia. Your goal is extremely dangerous, and you need to get a doctors advice before you start any dieting/exercise regime. If you are wanting to lose weight at where you are now, then you need help. Please don't drop weight just because others are pressuring you - you will face all kinds of horrible medical consequences if you remain at a dangerously low weight.
I am gonna exercise my butt off!! Literally!!