For MOST growing bodies, it is not healthy to maintain a body fat % below 7. However, some bodies are more mature, some kids naturally have less. Body builders normally have from 3-4 but they are also older. You can be below 7%, but it will require a doctors note to become certified. (In Ohio at least)
This system is bull , an average person has maybe 13 percent.... a wrestler has maybe 3 to 4 trust me all 4 years of highchool at 3 percent and nothing happened... but you body does need fat so nothing below the 3 percent
Dont worry about it it is not all that big a deal it is more of a legal thing to show that they are going to measures to keep wrestlers safe. I go below 7 percent everywrestling season. i dont know how unhealthy it is but nothing has happened to me from it yet.