Justin Bieber wowed fans by posting two shirtless selfies on Instagram, revealing he is "back in the gym."
In the picture, Justin is seen flexing his muscles while wearing just a towel slung around his waist. The Sorry hitmaker has obviously been working hard over the past few weeks as the results clear to see!
n January 2015, Justin was signed up as the new face of Calvin Klein underwear, and has since posed in several steamy campaigns.
His personal trainer Patrick Nilsson previously revealed he had worked hard to maintain the body he needed for the shots.
He told HollywoodLife.com: "He has put on 20 pounds of muscle and he's still working on it. It's a work in progress.
"We want to put on at least 15 pounds, he's going to get even bigger, that's the plan."
