The 26-year-old singer enjoys five 25-minute workouts every week with personal trainer Harley Pasternak, who says her brief workouts are better for keeping her trim in the long term.

Harley said: "It`s an intense workout that lasts 25 minutes. Working out more often for shorter periods is better than three times a week for longer.

"Katy loves jumping rope, so that`s what we do for cardio. It`s convenient, dance-like and expressive and efficient, time-wise."

Harley has also put Katy on a strict diet, where she eats five small meals a day, though once a week she can indulge in her favourite treats such as pizza and chocolate.

Harley explained: "She eats two meals and three snacks a day, consisting of healthy fats, lean protein, fibre and a non-sugar drink.

"Her favourite meal from recipes I`ve created is French toast - slices of bread dipped in egg white, skimmed milk and a little sugar, grilled and topped with low-fat ricotta cheese and berries."
sections: Celebrities