18 of 42:
Jordin Sparks, who won season seven of 'American Idol,' lost an estimated 30 pounds and posted photos of her slimmer figure in a polka dot bikini on her Twitter account. Sparks revealed that her weight loss was prompted by a 'shift' in her thinking, in which she made the decision to be more active.
(Pictured: Jordin Sparks appears in a still from her 'American Idol' audition. / Jordin Sparks appears in a photo posted on her Twitter account on May 1, 2011.)
(Fox / Twitter.com/TheRealJordin)