Britney Spears admits 'dieting is tough' as she shows off her incredible bikini body on the cover of Shape magazine.

She was snapped just last month displaying the dreaded curse of cellulite on her thighs.

But somewhat suspiciously, Britney Spears shows not a hint of it on the cover of the June issue of Shape magazine.

The 31-year-old shows off her incredibly toned figure in a white bikini on the cover of the fitness publication, but as is routine at most magazines nowadays, she appears to have got a little help from the airbrush.

But there is no denying the pop star looks back to her athletic best on the cover, wearing an elaborate white bikini as she poses with one hand behind her head and the other on her hip.

Her bronzed skin looks smooth and taut, and she flaunts a belly button ring, a throwback to her early days when she first hit the music scene.

She wore her hair in long tousled waves over her shoulders, and highlighted her lips with a dark pink lipstick.

Britney also sizzles in an inside spread in the magazine, including one shot where she is seen standing next to a punching bag wearing a black bra and figure-hugging skirt.

The star opened up about maintaining her famous derriere, telling the publication:

'I like it, then again, I hate it. I’m in my 30s now, so I have to work harder to keep it "up."'

Britney credits yoga and the Nutrisystem weight loss programs to keep her weight in check, but she said she is struggling to remain healthy.

'Dieting is tough… because my specialties are spaghetti, brownies and chocolate chip cookies,' she admits.

Britney was clearly excited about appearing in the magazine, tweeting a picture on Tuesday from the shoot and urging her fans to watch a behind-the-scenes video, airing later that night.