Determining a normal weight for a teenager is not as simple as pulling a number off a chart. Because a teenager's body is constantly changing during puberty, there are several additional factors to consider before normal weight can be determined.
Body Mass Index
The body mass index, or BMI, calculates weight versus height of a person and gives a range of numbers considered healthy, overweight or obese. However, this calculation does not take into consideration the fact that muscle weighs more than fat, so an athletic teenager may have a BMI that appears unhealthy.
Because of puberty and the constant fluctuation it causes, the BMI for teenagers is based on additional factors such as gender and age. For teenagers, doctors define normal weight as a percentile of a sample, fiftieth percentile being average.
Call Your Doctor If You Have Any Concerns
Different body types may cause a teenager to appear more overweight than they really are. Take your teenager to a doctor if there are any concerns about his weight. Paediatricians see thousands of patients a year and are the best judge of normal.