Megan Fox is back in fighting form!

Once criticized for being too thin, the 25-year-old revealed a healthier, more muscular bikini body while vacationing with husband Brian Austin Green in Kona, Hawaii, Sunday.

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The Friends With Kids star showed off her fit figure in a blue and white bikini top and black bottoms while wading in the Pacific Ocean.

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Kona, Hawaii, has become the go-to destination for Fox and Green, 38, who tied the knot in a private beach ceremony at the Four Seasons Hawaii in June 2010: The two visited Kona in June 2011 with Green's son Kassius, 9 (from his previous relationship with actress Vanessa Marcil).

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How does Fox get her body in such great shape? "Believe it or not she has this really fast metabolism," the actress' trainer Harley Pasternak said in 2011. "So her training is all about body toning and sculpting. With her it's really about she's eating enough of the right things."

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