Male 17 years old, height 169cm, weight 48kg. Is he normal in height and weight? Please give me some advice. Thank you.

Body mass index can be cited as a reference standard here.

At present, a common international standard to measure the degree of obesity and health is the body mass index as a reference.

That is body mass index = weight kg/ height m? The body mass index is normal at 18.5 ~ 23.9.

Your body mass index =48/ 1.69? ≈ 16.8, so you are thin.

I suggest you make a plan to gain muscle and weight, so that your body will become stronger and return to normal level.