Seeing Christian Bale's weight loss transformation for The Machinist in this thread reminded me of Jeremy Irvine's intensive weight loss for The Railway Man. Again, maybe not so much 'in the spirit' of this thread (as
@hazyshadeofwinter put it) as he looks pretty sickly (he played a *spoiler* tortured POW), but his dedication & discipline is incredible. He said his restriction led to him being hospitalised for 6 months after filming- I think he pretty much starved himself and his body crashed, didn't lose it gradually. (irrelevant but the guy's goddamn gorgeous!)
A picture of him beforehand for reference:
Another actor who lost a lot for a role (doesn't get mentioned very often for this) is Cillian Murphy. He lost 20 lbs in 6 weeks for In the Heart of the Sea. Picture is a bit rough looking as *another spoiler* his character gets stranded on an island (not many pictures as the scenes are limited). Probably my favourite actor and another utterly gorgeous guy.
His body usually for reference (from his show Peaky Blinders, he does work out a lot before filming for this. He says he's naturally skinny but he's filming so often he keeps himself more built):
He was also nice and skinny when he was younger:
(28 Days Later)
Disco Pigs
Surprised young Leonardo DiCaprio hasn't been mentioned in this thread yet:
The Basketball Diaries
Luke Pasqualino in Skins (good show for female thinspo too):
May not to be the taste of a lot of SG girls but Lil Peep (may he rest in peace) :
Konrad Annerud (model known for looking like Leonardo DiCaprio)
This was probably too long- kept thinking of guys to add to it! OT but would recommend all the films and shows in this post.