Is it normal to weight 56kg for a 16year old girl who's 171cm high?

Yes, a weight of 56 kg for a 16-year-old girl who is 171 cm tall falls within a normal range according to Body Mass Index (BMI) calculations. Her BMI would be approximately 19.1, which is considered healthy. However, it's important to remember that individual factors such as body composition, muscle mass, and overall health also play a significant role in determining what is "normal" for any individual. Always consult a healthcare professional for personalized advice.