Jessica Simpson Shows Off Incredibly Skinny Legs While Vacationing in St. Barts for 35th Birthday

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That St. Barts sun is hot, but it's Jessica Simpsons' legs that are making us sweat!

The clothing entrepreneur's bangin' bod was on display while sunning in St. Barts, where Jessica celebrated her 35th with two of her BFFs over the weekend.

Lucky us -- she documented her b-day adventures on Instagram.

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"I love these vacation babes," wrote the blonde bombshell, who turned 35 on Friday. Jessica looked relaxed as she rocked a black one-piece suit with a netted cover up, showing off what can only be the result of a lot of lunges. 

Jess is clearly hitting the gym hard these days -- just look at those legs!

As she posed in front of a picturesque ocean view, the mother-of-two was all muscle, a result of an intense workout regime she is obviously diligent about following.

In January, Simpson opened up to InStyle about dropping 70 pounds and getting her pre-pregnancy body back."I work out five days a week: three days with a trainer, doing a mix of strength training and cardio, and then I do cardio on my own the other two days," she revealed.

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But probably not this weekend! Based on her celebratory photos, the birthday girl was too busy having the time of her life.

On Friday, the day before flaunting those soon-to-be famous gams, Jessica simply captioned an Instagram snap of her wearing a Native American-style hat as "35," an age that is already suiting her well. 

And just last night, Jess posted yet another photo looking happy and carefree -- while also burning a few calories in the process! 

WATCH: Jessica Simpson Flaunts Slimmed Down Bod in New Swimsuit Campaign 

For more on Jess's new slimmed down figure, check out this video below: 

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