Lee Seung Gi revealed through an interview, “Historical dramas already have certain structures and appearances set so I wondered whether I could do a good job [through "Gu Family Book"]. Soompi reports that he said, "I can’t wear my hair in a way I want and there are limits with outfits, but the production team is doing a superb job and I can see my character from the script coming to life.‘He continued, “I’ve studied so I become more like Choi Kang Chi and look more like him. I wanted to look nimble so I enrolled in an action school after deciding on this project to learn more action moves through practice drills. "I’ve also practice horse riding so I can develop his skills. I also lost 6.6 pounds (3kg). Through this project, I want to show more of the character Kang Chi rather than Lee Seung Gi.‘Check out pictures of other K-Pop stars who lost weight in the gallery below.