Matthew McConaughey had "cheeseburgers for breakfast" in order to bulk up for his role in 'Gold'.

Matthew McConaughey

Matthew McConaughey

The 47-year-old actor was tasked with piling on almost 50lb for his role as prospector Kenny Wells in the upcoming crime adventure movie, and has admitted he loved having the freedom to be able to snack on fatty foods whenever he wanted.

Speaking on UK television show 'The Graham Norton Show', Matthew said: "I was a real yes man. Pizza night could be any night. Cheeseburger and beer for breakfast was a great idea too. I really relaxed on the rules. I was fat and happy."

And the star - who famously shed almost 40lb prior to his Oscar-winning performance in 'Dallas Buyers Club' - previously revealed he went on a "10-day fast" once shooting wrapped for 'Gold' in order to start shedding weight again.

He said: "Putting it on was easier and fun - cheeseburgers, beer, whatever I wanted.

"Taking it off, I did a 10-day fast just to kick-start my body into saying, 'Oh we're going without!'"

The 'Interstellar' actor's temporary diet also proved to be a hit with his three children, eight-year-old Levi, seven-year-old Vida and four-year-old Livingston - who he has with wife Camila Alves - who dubbed him "Captain Fun".

He said: "It was a wonderful ride. They were very happy. I was very happy with you know the Kenny Wells part of me that I brought home.

"My nickname was Captain Fun for six months 'cause I was yes to pizza night, even if it was Tuesday morning. I was yes to going to the carnival at midnight on a school night. I was like yes, yes, yes."

'Gold' will hit theatres on January 27.