Matthew McConaughey has been talking about his latest film role, playing a homophobic cowboy who dies from an AIDS related illness.

The Oscar nominated actor lost nearly four stone in four months to play the part of Ron Woodroof.

Dallas Buyers Club is the true story of a homophobic cowboy in the 1980s who is given only 30 days to live after being diagnosed with AIDS.

Unable to access anti-viral drugs in hospital, Woodroof turns to the black market for alternative medicines and succeeds in keeping himself alive for another seven years.

“He’s a real guy who has got this horrible disease and all of a sudden he’s thrown into a horror movie and he acts out of self-preservation,” McConaughey told Sky News.

“He’s self-serving. He turns into a crusader, almost unbeknownst to him, but he was always out for himself. He wanted to be a businessman, he wanted to roll in money.”

The script for Dallas Buyers Club was turned down 137 times over 20 years.

McConaughey’s co-star – the 30 Seconds To Mars singer Jared Leto – says the film has an important message and is helping to change attitudes.

“There was this kid the other day – we played Mexico City – and he said ‘you changed the way I look at gays’. That’s the way he said it.

“He said ‘thanks for that’ in a very innocent and matter of fact way. It just changed his perspective.”

Dallas Buyers Club is released in the UK on Friday.