The singer, 32, revealed her new look while performing on The Voice USA on Monday night.
Christina wore a sheer bodysuit as she performed her new single ‘How I Feel’ with Flo Rida. A source close to the star has revealed how she made her transformation.
The source said: “Her diet plan has been built around very small portions and very high energy training for short periods of time but frequently.
“Banned are dairy and carbs. On the agenda is coconut water, herbal teas, tofu, celery, oily fish and cheese.”
The source said that Christina’s weight-loss was for her own confidence, not because she felt pressured.
“Her body is hugely important to her and it’s one of the ways she gets her confidence- so being overweight was something she was never going to live with.”
And, while the results are dramatic, Christina insists she ‘doesn’t live at the gym’, saying: “If I can squeeze in a workout, great. If not, that’s OK, too.”
The star previously spoke how she makes herself feel sexy. Speaking to a US magazine, she said: “Trying too hard to be sexy is the worst thing you can do. Sexiness should be effortless.
“I’m such a down-to-earth girl, I’m comfortable in just a jersey and boy’s underwear.”
Christina’s fellow judge on The Voice USA Adam Levine was asked about her weight-loss on The Tonight Show with Jay Leno, and he only had good things to say.
When asked if, like Jay, he thought Christina seemed happier this year, Adam said: “No, that’s not your imagination. She looks great, she feels great.
“Also, we all know each other better so our chemistry on the show sort of improved.”