Britney Spears' Workout Video: Watch Here!

If you been wondering how Britney Spears got her super-toned body back, then wonder no more.

Brit's official website have posted a video of the singer being put through her paces by trainer Seven at her home gym.

The comeback queen – whose new single Womanizer is currently sitting pretty at the top of the US chart – works out with Seven four or five times a week, complimenting her gym work with intensive dance rehearsals in preparation for her upcoming tour.

It's been reported that Brit has also given her Frappuccino-heavy diet an overhaul in a bid to get back in shape.

"She limits herself to 1400 calories a day with one 'cheat day' where she'll treat herself," says a source.

"She also changed the way she eats, trying to have only two thirds of what is on her plate. It's all about portion control and fresh food now. And lots of water in place of Red Bull."

And all the hard work seems to be paying off - see Brit working up a sweat below