I suspect a whole lot of her apparent premature aging is due to her very sensitive skin. Go find some candid pics of the girl at age 16 or 17 and you'll see her entire face and shoulders are very heavily freckled. That's a sign of skin that's extremely prone to damage even from moderate amounts of sun.
Combine that unfortunate genetic trait with weight loss (that's made her face more angular) and you've pretty much got her current appearance.
Combine that unfortunate genetic trait with weight loss (that's made her face more angular) and you've pretty much got her current appearance.