as someone who had/has an ed, I thought the same, but it coul also be a bit of illusion? the jacket is very baggy, creating a significant difference in volume between her lower and upper body, the picture is chopped which adds up to this THInspO aesthetics (aka your eyes are automatically drawn to her legs), making it seem like it's her upper thighs but it's actually above her knees...if you look at some other photos, she is still very skinny but not
this skinny.
However, I do think there's something very problematic going on -- if you have the urge to appear twiggy-like thin, especially when it's not your natural body type (and we all saw her show-your-thigh-gap and lengthen-your-legs pics), you can't have a healthy perception of your body -- I learnt that the hard way.
She's in the industry where looks are considered very important, and both lizzy and lindsey have turned their bodies into their greatest assets, which only perpetuates the same successful/happy/pretty=thin patterns and forces them to stick to it unless they would be willing to be more authentic and less "trendy", which eeeehm, I doubt will happen any time soon. (I mean just look at Hannah F, she gained some weight, and it pops in her thread every so often in negative connotations. The border between "oh god she's too thin" to "oh go what a fat cow" is really thin. For people and even more for fashion companies.)