My son is 18 and has been trying to join the Army for the past 7 months on both occasions at Worcester AFCO he keeps being told his BMI is to low. He is 6ft and 8st 11lb I know this is skinny but he is gyming it everyday and eating like a horse I believe that at such a young age his metabolism isn't ready for him to turn into hulk Hogan, so what is the answer to this? He is fit as a fiddle can do pft in 9:15 and as I said before at the gym 5 times a week. All he keeps getting told by the civvies is put weight on which is easier said than done. Is there a way of contesting this or taking it higher please?