Beyoncé has revealed her struggle to lose the weight she put on whilst pregnant.

The superstar singer gave birth to daughter Blue Ivy Carter in January 2012 - her first with husband Jay-Z.

Speaking to Shape magazine, the '4' star admitted that she gained 57 pounds during the pregnancy, which she had to shed quickly.

With a live show booked only months after giving birth, Beyoncé revealed that she had to work out hard to get back in shape. She said:

"I gained 57 pounds when I was pregnant. I didn't have a lot of time to lose the weight, because I scheduled a show three months after I gave birth, which I would never do again."

The singer added: "I'm not a person that is naturally very thin. I am a person that has to work at keeping my body in shape."

Beyoncé meanwhile is due to embark on a world tour in 2013, with many dates selling out almost instantly.