Adipose tissue (body fat) is bad beyond 10% for men, and beyond 20% for women. However men with uber-low bodyfat (in the 3% range) is bad, because they lose their ability to procreate and have children (they lose their mojo, or their fertility). Same goes for women — women with single-digit bodyfat is bad, because they lose their ability to have children as well.
To have a 6-pack is good for both men and women. But when you get too “insanely shredded”— this ain’t good.