I mean also for women you put body functions at risk if you go too low body fat. Which is why a lot of women with extremely visible abs only go like that for like two weeks, take heaps of pics, then release those over the year to create the illusion that they have those abs all year around.
This is ofc also up to genetics but yeah in the vast majority of cases it's not healthy, only very few women have very defined abs when their body fat is on good levels. Mags/omgcosplay never looked unhealthy "fit" so to say. Takes a lot of dedication and sometimes starving to get there, you don't end up there accidentally. Just like you hear some men, when they start going to the gym, saying stuff like "I don't wanna get too big" like trust me, you won't.