I can no longer tell if I'm "sucking it in"

Factual Questions
1

For about fourteen years of my life, I was chubby and very self-conscious, to the effect that I was always sucking it in. It became an automatic thing that I didn’t have to think about. Then, two years ago, I lost all that weight and now I’m pretty skinny. Like about 9-10% bodyfat skinny.

But I’m not sure if I’m still sucking it in or not. “Relaxing” and “pushing out” feel about the same, to the effect that “relaxing” might just be pushing out to a lower degree. I’m really not sure.

So, fellas? Is it dangerous if I am? I’m not uncomfortable, just a bit curious.

2

Well, if you’re constantly “sucking in” I imagine you may feel fatigued slightly. If you lost the weight through rigorous exercise and abdominal workouts, it could be that you really are that slender now. I know when I do ab workouts my stomach tightens up to the point where it feels and looks like I’m sucking in, but not.

3

Yeah, I can tell when I’ve been holding it in more than usual because my back starts hurting for no apparent reason.