In one confronting photo, a rail-thin Leto poses side on to Richardson's camera, holding his t-shirt up to show off his emaciated figure. In another shot -- a close-up -- a haunting Leto stares into the camera, revealing his gaunt, sunken cheeks and missing brows.

Leto shocked onlookers at Monday's IFP Gotham Awards when his sans-eyebrow status (as well as weightloss) became apparent.

Speaking to Vulture after the show, he apologised for his weight-loss induced light-headedness, as well as explaining the reason for his appearance.

His first film role in four years, Leto said: "I'm playing a transsexual woman," adding "I didn't get involved in the project until a few weeks ago, three and a half weeks ago."

Since signing on to play a transsexual woman dying of AIDS, the actor hasn't eaten, telling the Gotham Awards host Mike Birbiglia on Monday: "I haven't eaten in 21 days." He also revealed a newfound respect for women saying. "It's a lot of work to be a pretty little girl." Especially when you wax your whole face and body.

This isn't the first time Leto has lost or gained weight for a film. In 2000's "Requiem for a Dream," he lost weight to play a drug addict. In 2009's "Mr Nobody" he gained 27 kilograms to play Nemo, the last mortal on earth.

Despite his previous experience with role-related weightloss and weight gain, Leto is apparently concerned about doing it in a healthy manner this time. "Your body goes through weird stages," he said. "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."

Leto is also hoping to have a spiritual transformation from his fasting. "Historically, people have done it for pursuit of self, to achieve a meditative state," he told Vulture, adding "So I'm hoping for that, and not the other things."

"Dallas Buyers Club" co-star Matthew McConaughey has also lost an alarming amount of weight, bottoming out at 65 kilograms (a weightloss total of 17 kilos) to play the lead role, also and AIDS sufferer, in the film.

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