be (as) thin as a rail

To be extremely skinny or slender. Primarily heard in US. Have you seen Claire lately? I'm really worried about her, she's as thin as a rail! I've always been thin as a rail, even when I tried to gain weight.

Common Names:

Name	Pronounced	Usage
Sasithorn	-	Thai
Nico	NEE-ko (Italian, Dutch, Spanish)	Italian, Dutch, German, Spanish, Portuguese
Tiphanie	-	French
Hamilton	['hæmiltən]
Tiffiny	TIF-ə-nee	English (Rare)
Anargul	-	Kazakh