Isn't it unhealthy for it to go so low? I remember once mine was around 7%. Years ago. I still have no fat nor muscles. At least I have something similar to the holy Cure D'Ars, even if not the virtues.
Not as long as your blood is healthy. Fitness and blood oxygen-supporting nutrition helps maintain healthy blood. If you get dangerously low, simply eat more healthy fats to get you out of that danger zone.
Btw, 7% isn't too low.
Men should not be above 10%, and women should not be above 15%. If they are, they're eating too much dietary fat - even if it's healthy fats. Women should have higher body fat % as it's for child-bearing and it's their natural composition due to their hormones levels being different then men's levels.