Rachel Bilson Flaunts Bikini Bod in Barbados with Shirtless Hayden Christensen

Rachel Bilson showed off her tiny bikini body while on vacation with her beau Hayden Christensen on April 11, 2012 in Barbados. FameFlynet

Who knew Dr. Hart had such an awesome beach bod underneath that white coat?

Rachel Bilson stunned when she hit the surf in Barbados Wednesday with on-again love Hayden Christensen by her side. The Hart of Dixie actress, 30, rocked a black halter top bikini as she swam with her boyfriend of five years. (Bilson and Christensen, 30–who have dated since 2007–split briefly in 2010, only to reunite a few months later.)

"Rachel and Hayden went into the water and were kissing…They were really sweet together," an eyewitness tells Us Weekly of the actress' beach outing. "At one point, Rachel was playing with her half-sister, Rosemary, and helping her build sand castles."

When it comes to staying in shape, the former O.C. star has spoken before about her workout and diet priority: feeling as healthy and happy as possible.

Last fall, she opened up to InStyle UK about choosing not to let the number on the scale, or what other people might be saying about her, dictate how she feels about herself.

"I eat, I love food, I wanna eat when I wanna eat," she told the magazine. "If you are not feeling good…then you work out. But you do it for you."

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