11% is the standard accepted number. Some women can go as low as 7% (maybe lower) and still have her periods (which does not mean that it is healthy however. So let’s take 11%.
Let’s step back to the biological passport. Cycling started that whole thing. They knew they could not catch EPO users (because traces of it is all but gone too quickly), but they could see that your hematocrit levels were too high. They would then say that you can’t compete if you are above X because you are “overtraining”. And you should rest up before competing (as it would be unhealthy for you to compete at these levels). So the concept is out there. If the sport federation feels that you are getting in the unhealthy spectrum, they can ban you from competing.
What about that. If a woman fat % is below 11%, then she can’t compete. They should be resting and get a little fatter. That would stop this unhealthy obsession to get more and more thin.