i run for about 3 miles a week and do 45 minutes of ballet a week too. (but the ballet wouldnt amount to much excersise) i would like to lose 20lbs ideally, so if i lost 2lbs a week, how much excersise would i need to do? i dont have time to do much else, so if i kept the running and ballet up, how many pounds would i lose a week approx?

im 14 years old, 171 cms tall and weigh approx 63 kgs. and i know my bmi is 'healthy' but im not happy with my body.

thankyou'x