Not even in these photos? . . .
Actually, I don't know that she's too thin in those photos.
She's too thin, for me, but that's not the same as being too thin. I think most actresses/models/famous women look too thin, but while that may be true, it doesn't mean they're unhealthy. Also, it's not odd that Juno thinks she doesn't look too thin, as I'm sure that most people who are in or want to be in that world don't think she looks too thin. That's normal. Desirable. Necessary, even.
As for the pic, her arms don't look good, but that's not because they're too thin, but because of the lack of elasticity of her skin. That's why the older you get, you need a little bit of fat to 'fill out' and you'll look better. When I first saw that pic, I thought it might be Kate Beckensale. She's another who I think often looks 'too thin' but, for reasons I don't understand beyond women liking her and not selling as many copies as Jolie will, she not only gets away with it, but is often held up as some vision of naturalness (which is ridiculous, considering the amount she's had done.)
Secondly, she doesn't appear to have, what I call, "lollipop head". That is, her head doesn't look too big for her body, which is usually a dead giveaway that someone's too thin. That, or has an enormous head.