Is it healthy to be 112 pounds if you are a 13 year old girl and are 5 feet 5 inches?

For your height 5'5 and weighing 112 pounds, your BMI (body mass index) is 18.6. Underweight is anything under 18.5. Simply put you are in the healthy zone, but borderline healthy. Gaining a few pounds could be very beneficial to your health.