The actor loved piling on calories and dined on pizza, burgers and beer to get into character as chain-smoking Kenny Wells in the new film, and admits his wife Camila Alves and their kids also loved him a little chubbier - but his mum wasn't so keen on her son's unhealthy lifestyle.

"My mom was very happy until I got close to 200 pounds, and then she was like, 'All right, fat-a**, that's enough already. You look like you got two pigs wrestling in your trousers'," Matthew tells Playboy magazine.

But the Oscar winner's brother Rooster loved Matt's new look - because it reminded him of their late father.

"My brother said, 'It's Pop all over again'. He thought I was so loosey-goosey and fun, he didn't want me to take off the weight."

MCConaughey admits he thought a lot about his dad while playing Wells in the film.

"Oh man, he loved to eat, drink and host. He was six-three, six-four and weighed about 260 pounds at one point."