if he gained more weight, his face would get chubbier. You can relate it in his old movies and series. Based on his preference of choosing his roles, the roles mostly demand him to stay slim to either fit the character or to look sharp when being filmed closeup.
Oh,,, is that true? okay thanks for the info. I'm very concerned about his very thin body. I prefer him to have an ideal and muscular body Definitely more handsome
It's difficult for him to gain weight he said that many times that no matter how normal he eats or sleeps, he doesn't still gain weight he even workout. Also, it depends on the role that was given to him. For example, tantai jin in till end of the moon should be really thin because he was in poverty for so many years and being abused.