Being tall just means that the bones are elongated, but it doesn't mean that the meat on your body will be reduced. On the contrary, with the elongation of bones, nutrition will be properly supplemented to achieve balance. Therefore, it is not necessarily that the body will be thin.

But on the other hand, the above is not necessarily absolute. Many people will lose weight obviously in the process of development (this situation is more common in boys), and the physical development of girls is different from that of boys (girls will gain weight).

Suggestion: Don't lose weight, because you are only 13 years old and still developing. Just control your diet a little and eat more fruits and vegetables.