Weight in measuring human body weight in the medical sciences and in sports is a measurement of mass, expressed in units of mass such as kilograms or pounds. In Britain, the stone (14 lb = 6.35 kg) is still fairly common for this purpose as well.
The average weight for male adults in the United States is about 168 to 183 lb (76 to 83 kg). The average weight for male teenagers in the United States is about 99 to 141 lb (45 to 64 kg). For female adults the average weight is 120 to 140 lb (54 to 64 kg). For female teenagers the average weight is 100 to 126 lb (45 to 57 kg).
Note that textbooks in fields such as physics and engineering often use the term weight for particular kinds of force, and often express body weight in force units such as newtons and pounds force. Thus we get the commonly held notion that "your weight" would change if you went to a different planet, which is not true for the word weight as used in medicine and sports.