Article continues below advertisementMeghan Trainor has been putting in work at the gym.The pop star's fitness instructor, Bella Maher, showcased her dramatic body transformation in an Instagram post on Sunday, October 26.The social media share featured side-by-side photos of Trainor, 31, who previously revealed she took a GLP-1 to aid with weight loss.Article continues below advertisementSource: @malibubodies/InstagramMeghan Trainor works with a coach in the gym."Watching her transform from the inside out has been one of the most meaningful parts of my work," Maher gushed of her client.