SISTAR member Soyu shared a secret to her successful diet recently on Twitter. The star lost almost 18 pounds (8 kg) for SISTAR's comeback with their new single, "So Cool". Soyu tweeted, "The temperature gap from morning to evening.. Please be careful of seasonal colds. I'm on a diet these days, it's really difficult. But let's be 'so cool' today as well!!" She also posted a photo of her meal, which consists of two boiled eggs, boiled broccoli, and pieces of pineapple. Fansresponded, "So this was the secret to your amazing weight loss," "You dance after eating a meal like this," and "Not everyone can have a body like that." Source + Photo: Newsen via Nate