As we try to start the New Year with a health kick to rid ourselves of the Christmas excess actor Matthew McConaughey has spoken out about how difficult he is finding it to gain weight.

The 44-year-old star has revealed he's struggled to gain back the weight he shed for his acclaimed role in the soon-to-be-released Dallas Buyers Club.

In order to portray an Aids sufferer in the movie, the actor lost 50 pounds, leaving him looking gaunt and emaciated.

Speaking to, McConaughey explained he is finding it tough to regain the weight as his body is used to being starved.

He said: "I gained 45 (pounds) of them back. The gaining was trickier than the losing. It's more fun, but it's also trickier.

"The first big meal that you eat, your body remembers that it lived at 182 pounds and it wants to sprint back and you have to pull the reigns and go, 'Woah! We gotta take it easy.' It's a marathon."

Dallas Buyers Club is released on February 7.