Lee Sung Kyung sat for an interview at a cafe on January 12 where she admitted to being depressed by some aspects of playing Kim Bok Joo in 'Weightlifting Fairy Kim Bok Joo.'

SEE ALSO: Ahreum breaks up with boyfriend & claims he coerced her to commit fraud

"Early on, I did 'Doctors,' and then haven't been able to take a break since, so it was hard for me," she revealed.  "For 'Weightlifting Fairy Kim Bok Joo,' I ate floury food and worked hard to gain weight.  Honestly, saying 'gain weight' means it's not good for the body.  When I gained weight and acted as Bok Joo, I was fine, but when I was myself, I felt different and my clothes wouldn't fit, so I was somewhat depressed.  My fat was sticking out and this body could be irreversible and my skin got bad.  I was depressed when I was myself again. However, when I started up [acting] again, I did so happily."