13-year-old girls have an average wight of 45.8kg (101lbs)
So in your case, you're either tall or muscular, but cannot be considered neither fat nor obese - you are healthy, and are not in the need of loosing weight.
Hope it helped,
BioTeacher101
Your perfect! Your weight is just right! Stay in the 20s and you won't have to gain or lose weight.
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