A source close to the star told People magazine Adele was motivated to give her health an overhaul for the sake of her seven-year-old son, Angelo and adopted a new fitness regimen earlier this year.
"At first, she was very hesitant about keeping a workout routine. It was like she was questioning if she was gonna enjoy it enough to stick with it," the insider said.
"But she has been incredibly dedicated."
A source close to the singer said Adele adopted a new fitness regimen earlier this year.
Adele's routine now includes regular sessions with a personal trainer, reformer pilates classes, and workouts at the Hollywood-loving Rise Nation, a Stairmaster-inspired class.
Another source added that she's also "watching what she eats".
"She has taken a more serious interest in improving herself and is actually having a great time," the friend revealed.
Adele first surprised fans with her smaller frame when she posed alongside the Spice Girls in June during their reunion tour.
A source close to the star told The Sun at the time: "Adele has been out enjoying herself and she sees that as her priority at the moment, along with being a mum to Angelo.
"She has been loving her new workout regimen and it really works for her.
"It's a bonus that she has shifted some weight.
"Her mates are glad she's letting loose and there's nothing but good feelings towards her. She's got a new lease of life."