Rihanna works out at 4am. The 'California King Bed' hitmaker is so determined to stay in shape at all times, she adjusts her lifestyle in order to accommodate her fitness sessions, even getting up extra early to make sure she doesn't miss out on her daily physical activities.

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Her trainer, Ary Nunez, said: “Rihanna trains as much as she can, whenever she can.

“This could be every day or three times a week. Her work schedule is extremely demanding, so thank goodness she’s naturally a hard-working person.

"We make time and find time – whether it is at 4am or 9am.”

According to her trainer, the 23-year-old beauty is even willing to work out while having her hair and make-up done.

Ary added: “We always squeeze it in.”

While Rihanna works hard to maintain her toned physique, Ary believes she is naturally in good shape because it doesn't take long for her to look her best. To keep her weight to be low, she does a lot of cardio workouts such as treadmill and running. Also, she often include dancing for her cardio workouts. Rihanna does and some weight training. Some of her favourite exercises are lunges and squats.

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She told the new issue of Britain's Star magazine: “Rihanna has a gifted physique. She can become lean, get ‘baby guns’ [biceps] and firm up her core quickly. Her physique is the epitome of classic beauty, it’s feminine, strong, agile, poetic and versatile.”

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"Chocolate ice cream is her comfort food. She says to me, ‘I need my quota.’ I believe deprivation leads to disaster, so I don’t stop her – that’d be asking for trouble. Rihanna does not follow a diet although she tries to eat healthily on tour. She loves protein-rich foods, water, olives and fruit. She’s in tune to how her body reacts to different foods."