your best weight depends on several factors besides your age. How tall are you? What is your body type, i.e., small boned, large boned, average boned, medium boned. The best thing to do is type into your internet, "Ideal weight, or what is my ideal weight"? The internet will help you figure it out. I am 5'11" tall and my ideal weight would be 105 lbs. (if I were younger) to 112 lbs. I have a small frame.