Nowadays, it's hard to find much body fat in Hollywood.

Today's stars are slim and toned, whittled to within an inch of their lives.

When pressed about their slimming secrets, celebrities often rave about their "good genes", their affection for junk food, or declare that their secret to staying thin is simply running around after their children.

Slim stars - LEFT: Paris Hilton CENTRE: Lindsay Lohan RIGHT: Britney Spears

But here's what you should know: a lot of them are lying.

Celebrity trainer Gunnar Peterson, who has trained Angelina Jolie, Jennifer Lopez, and Penelope Cruz, says: "I had one actress training with me four times a week in addition to daily exercise bike classes.

When the Press asked how she'd 'transformed' her body, she said: 'Oh, I do yoga and hike with my dog.' It makes me laugh."