An height of five feet and 8 inches at the age of 14 years indicates very good growth. Medically, a 14 years old boy with an height of five feet and eight inches should have an weight of 125 pounds or 57 Kg. You should not be much concerned about your weight at this age if you are slightly overweight because you are still growing and need energy to maintain growth. This energy can be obtained from good diet.
