Matthew McConaughey, Jennifer Garner and Jared Leto hit the red carpet for the premiere of homophobic cowboy's AIDS tale "Dallas Buyers Club."

BEVERLY HILLS, CALIFORNIA, UNITED STATES (OCTOBER 17, 2013) (REUTERS) - The stars of the new film "Dallas Buyers Club" hit the red carpet premiere in Beverly Hills on Thursday (October 17).

Matthew McConaughey plays Ron Woodroof, a homophobic, hard-partying Texas cowboy who suddenly finds himself facing an HIV diagnosis and given 30 days to live. Refusing to give up, McConaughey's character embarks on a journey to find a cure and learns about unapproved treatments that are being used in Mexico. Woodroof smuggles the medicine into the US to dispense to other HIV patients.

McConaughey lost 40 pounds for the role and described how he was able to transform himself into the dying AIDS patient.

"This was a real guy who went through these real events," said McConaughey. "He gave me plenty, an endless amount to grab a hold of and feel like I needed to become a master of. So you look for that, you look for something you grab a hold of and hang your hat on and say 'Now I can dedicate myself to this for nine months.'"

The film is set in the mid-to-late 80s when HIV and AIDS was starting to emerge. During the filming, McConaughey was reminded of his own memories during that era when people were panicked by the unknown and deadly disease.

"I remember there being a lot of paranoia and I remember there being a lot of questions and nobody had any straight answers or at least no one had consistent answers," he said.

The movie also stars 30 Seconds to Mars frontman Jared Leto who plays Rayon, a transgender and fellow AIDS patient. Leto also lost weight for his role as he transformed himself into a woman.

"It was a role of a lifetime, I really fell in love with Rayon," said Leto. "I lost 30, 40 pounds, put on the heels, waxed my body, changed my voice."

Jennifer Garner talked about her co-stars startling transformations during filming.

"It was upsetting but it got more upsetting as time went on," she said. "I hated it and I just wanted him to eat. I just wanted it to be done, I hated, hated watching him, just quietly whither away. He never complained and neither did Jared. But the great thing about both of them is that their performances transcend the weight loss and they really pulled it off."

Based on a true story, Woodroof was able to help dozens of people. Woodroof lived with his diagnosis for six years and eventually died on September 12, 1992.

Dallas Buyers Club hits theaters on November 1.