They dont, hating themselves and never bothering to change because they hate themselves too much to even begin to put in effort.
As well all know, most women, and people in general, feel something's useless and pointless, they WILL NOT try to fix it.
By healthy they mean, not actively experiencing any pain or underlying issues aside from just having extra fat. Like they're still fat, but they aren't so fat that they'd probably die if they were to excercise.
That's what they mean by healthy.
I can see how it might sound like that though. But its hard to put into a short 20 word or less sentence so it just comes out as, yes I'm fat but I'm as good and healthy as any other person.