Group f(x)'s Sulli revealed her diet secrets.

In SBS "Star King" aired today, Sulli came out and revealed her diet secrets.

Her plastic bag diet was simple. She blew air into the bag and hit the bag up with her knees, working out that way. Sulli showed the diet skills herself.

Sulli said, "It's not hard and it doesn't require much energy so even non-athletic people can follow it."

Internet users who saw this commented, "It was that simple?," "I'm going to try it right now," and "Would that really work?"

Photo Credit: SBS