Singers Soyu and Kwon Eun Bi shocked everyone by revealing the extreme diets they went through as members of a girl group. The episode of SBS's 'Strong Heart League' that aired on July 25 KST set a new record for viewership, with a rating of 4.7% and an average rating of 3.5% (based on households in the metropolitan area).

During the show, Soyu shared her experience with an extreme diet. Despite gaining popularity for her exercise content on her YouTube channel, Soyu explained that she had intentionally gained weight for content and then tried to lose it. She aimed to reach 65kg and was able to gain weight after three months, after which she lost the weight she gained.

Soyu also shared her past struggles with weight during her time as a member of SISTAR. She explained that at debut, she was naturally thin and didn't gain weight easily. However, she found herself rapidly gaining weight with the chaotic schedule she had at the time. Determined to shed the extra weight, Soyu decided to embark on an extreme diet. "I ate four quail eggs a day without the yolk. I practically starved. With exercise I was able to lose 8kg in a month."

Kwon Eun Bi also opened up about her own experience with weight loss as a trainee. She revealed that she had to lose weight to fulfill the industry's beauty standards and increase her chances of debuting. Her extreme diet involved eating only sliced apples for breakfast, with one apple slice consumed each hour. In this way, she survived on just three apples over three days, which surprised everyone.