0229_rihanna_singleRihanna may have been joking when she tweeted a shot of herself working on in a bikini (and bare feet) last month, but her trainer says she's very serious about her workouts.

Celebrity trainer Harley Pasternak recently detailed the pop star's rigorous regimen to People.

Despite her travel schedule, Pasternak says Rihanna tries to work out three times a day for 25 minutes each. But once she settles in a location, her training intensifies.

"She's been really focused and stepped it up," increasing her sessions to five days a week and bumping her cardio to a total of 30 minutes a day from 10," Pasternak explains.

Among her favorite cardio activities: biking, jogging, and judging by the photo, elliptical training.

As with any exercise regiment, diet is equally important.

Rihanna eats five small meals a day, but will occasionally get "salty cravings" which she satisfies with Pasternak's high-protein, bean-based 5 Factor chips.

Perhaps beans are the magical fruit, especially if they get results like Rihanna's!

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