Jared Leto is hoping to achieve a "meditative state" by fasting.

The 40-year-old singer-and-actor was cast as a transsexual woman in new movie Dallas Buyer's Club - for which co-star Matthew McConaughey has dramatically lost a huge amount of weight - and is taking his diet to the extreme to look right for the role, though he admits it has sparked some "weird" effects on his body.

"I'm playing a transsexual woman. I didn't get involved in the project until three and a half weeks ago. Your body goes through weird stages (when fasting). Sometimes it's hard to hold on to water. But for me, it's not about the most weight I can lose, it's more to represent the character. I'm focused on what it means to be a transsexual woman. Historically, people have done it for pursuit of self, to achieve a meditative state, so I'm hoping for that, and not the other things. It's not necessarily a bad thing," he told Vulture.