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That's the price of a new Pilates video by Mari Winsor, the trainer and Pilates guru Cyrus credits with helping her shed nearly 10kg.

The new DVD, called 'Lower Body Pilates', focuses on the hips, glutes, and inner and outer thighs.

According to Winsor, while the exercises work out the 'rear view', they also tone the tummy as the abdominal muscles are always engaged.

Winsor told media that "in Pilates, every exercise that you do is focused on your abs, or as we call it in Pilates, your powerhouse. The 100, the double leg stretch, and the criss-cross are all crucial to sculpting your abs."

Bondi-based trainer Libby Babet from Bottoms Up Fitness agrees that Pilates is an effective form of exercise for women who want to strengthen their core.

"It's safe, effective and gentle BUT strengthening or toning your core and achieving a flat tummy like Miley has done are two very different things," says Libby. "You can 'tone your abs' all you like but if you've got a layer of fat covering them up, you'll just end up looking even bigger in the tummy!"

If you're after a flat tummy, Libby recommends a combination of excellent nutrition, lots of water, plenty of sleep, fat burning exercise like interval cardio, and resistance training.

"Try circuit or reformer pilates classes, or hire a PT to show you the ropes!" she advises.

If Miley's 'transformation' looks like hard work, that's because it is! But that doesn't mean that it's impossible, as long as you're motivated, says Emma Seibold from Melbourne studio Barre Body.

"Any really motivated person can achieve great results with effort and commitment," she says.

Cyrus, who is engaged to Aussie actor Liam Hemsworth, also cut out lactose and gluten from her diet to slim down.

Back in April the 19-year-old popstar tweeted that she thought everyone should give gluten-free a try. "The change in your skin, physical and mental health is amazing. You won’t go back!" she enthused.

She's right to modify her diet too, says Emma.

"A healthy diet is absolutely crucial to losing weight. Think of it this way...a healthy diet equals the right weight. Exercise equals toned shape."