Seventeen's Seungkwan showed off his weight loss success! 

During the December 5 album showcase event for Seventeen's third mini-album, 'Going Seventeen,' the members talked about the intensity of the choreography for "BOOMBOOM." 

SEE ALSO: 1TYM’s Song Baek Kyung shares life after retirement

Seungkwan said, "It's an automatic weight loss because the choreography is so intense. It's a 'BOOMBOOM' diet. Even if I didn't try to lose weight, I naturally burned fat and lost weight. My face became better looking. I asked Hoshi to continue to make difficult dances." 

He then added, "I got fat after Chuseok (Korean Thanksgiving). I was discouraged. I wanted to become good looking because I am a singer. So I watched what I ate and did burpees; I lost 7 kg (~ 15 lbs). I will maintain it." 

Check out Seventeen performing "BOOMBOOM" during their showcase below!