The 32-year-old superstar singer did some shopping with a friend at Barneys New York, taking time to smile and wave for the cameras as she got into her car.
And if it looked like Aguilera was glowing, the secret to her new body transformation might be the reason.
Sources confirmed to E! News recently that Aguilera made some healthy changes to achieve it.
"[She's] making herself a priority, trying new exercises and trying things she loves and enjoys rather than stuff to just 'lose weight,'" the source said. "This is really from the inside out."
Aguilera first showed off her slimmer figure in May at the Billboard Music Awards, making jaws drop when she hit the stage with Pitbull for a performance of "Feel This Moment."