The 22-year-old stripped down to a black bra and knickers to reveal her tiny waist and washboard stomach, which she claims is down to cutting out carbs and booze for nine days.
Sam captioned the pic: '#photoshoot 9 days no alcohol, no carbs & training.'
Now, call us cynical but Sam's new regime wouldn't have anything to do with the fact that her ex, Joey Essex, is currently flirting for England with a certain Amy Willerton on 'I'm A Celeb', who loves nothing more than stripping to her bikini for a jungle shower or five?
Amy Willerton and Joey Essex have grown close in the 'I'm A Celebrity' jungle
Sam has lost over a stone since June thanks to an intensive diet and regular gym sessions with a personal trainer.
A source told Closer magazine: "Sam really likes her new shape. She's been working hard and is thrilled with the results.
"She's determined to look her best in her bikini. Even when she was in Dubai recently, she was doing 500 sit ups every day."
But despite being in the best shape of her life, her sister Billie says Sam is finding it tough watching Joey getting on so well with Amy on national TV.
"It's never nice to see your ex flirting with someone else - it's not a good feeling," she told Closer. "Sam is quite tough. She's keeping her chin up and doing fine."