Britney's Back In 'Shape' & Flaunting It!

Shape Magazine

Britney Spears is baring her toned physique as the cover girl of SHAPE magazine's June issue -- and she's revealing her weight-loss secrets.

The 31-year-old pop princess reveals her workout regimen, telling the fitness publication, "I'm doing 90 minutes of yoga twice a week in addition to a lot of cardio, hour-long sessions three times a week, with my trainer, Tony Martinez."

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It's certainly paying off for the former X Factor judge who also revealed that she follows the Nutrisystem program, a shake for breakfast and lunch plus a dinner of protein and veggies. Spears admits that it's tough for her not to over-indulge in treats with her sons Sean and Jayden. "I try not to make those too often or I'll eat the whole bowl of dough."

While Spears' songs are most certainly on gym-goers playlists, what gets this Slave 4 U singer amped up? Spears tells SHAPE that she listens to Whitney Houston's I Wanna Dance with Somebody and Bruno Mars' Locked Out of Heaven.

For more with Britney, check her out in SHAPE when it hits newsstands (and iPads) on May 20th.