Change his appearance or something :) Not too comedy, I want to take the "change" a little serious

At the moment there is oh my Venus where shin min ah has to lose weight for her health and also bubblegum has two severely damaged people 1who is trying to get psychological treatment for a childhood trauma hope this helps ????
she was pretty
Heart to heart (although the change was gradual) - v good under-rated drama
Dream High (side story)
Birth of a beauty

J-
Yamato Nadeshiko Shichi Henge
Nobuta wo produce

Growing Through Life (TVB)
All S.Korean, Movie, Show

Fly, Daddy, Fly
Innocent Man 
It's Okay, That's Love
Old Boy
Pluto

School 2013
White Christmas 

Idk if they're all in the way you're thinking. Some of them change in different ways than the others on the list. If you want a bit more explanation, message me and I'll try to explain without giving too much of the plot away ^_^ If you're specifically looking for change in appearance then italicized 
first and only thing that came into my mind: King Flower!! 
If it doesn't have to be a change about looks/physical appearance....

I think The Innocent Man fits this description pretty well. 
http://kissasian.com/Drama/My-Amnesia-Girl

An Asian film, a romcom with a twist. The female lead changed because of the past. (for a change) haha but you can just ignore this coz it doesn't fit your description but its a good watch so I am recommending it. ^^
Birth Of Beauty, The Innocent Man , School 2015