However, the ballad singer was seen going through some severe withdrawal symptoms as he reacted sensitively and harshly to various moments in the show.�Members of the variety show then gave him the nickname 'Sung Glass (Sung Yuri)', stating that the singer's mentality had gotten even more sensitive and fragile now that he has quit smoking.�

When Sung Si Kyung was asked if his appetite had increased because he quit smoking, the singer responded, "Even when I did smoke I had a big appetite. So I don't think that it will get any bigger."

According to Jung Hyung Don, who had gone to a buffet with the singer in the past, Sung Si Kyung is known to have one of the biggest appetites among Korean celebrities.

Actor Shin Hyun Joon then added jokingly, "It's because he is good-looking, but [his body isn't so good-looking]."

In response to Jung Hyung Don's statement, Sung Si Kyung said calmly, "I think it's polite to binge eat at buffets," as he explained the steps that he takes when he is at a buffet.�