Why Jennifer Lawrence puked before Joy premiere

Jennifer Lawrence has blamed nerves and exhaustion for falling ill before the recent New York City premiere of Joy, confessing she vomits whenever she is stressed out.

The Hunger Games star admits reports of her feeling sick just hours before walking the red carpet are true, confessing she has been working non-stop.

"I puked yesterday," she told US talk show host Stephen Colbert. "I'm a puker. I'm a big-time puker. I think I have, like, nervous (energy)...

"I think that I don't stop working, because I'm a show pony. I don't have a choice. So, I just keep going, I think, until eventually my body's just like, 'If we don't make her barf or pass out, she won't stop'."

Jennifer Lawrence in a scene from the movie, Joy.

Making a quip about fellow actress Lindsay Lohan's former party girl reputation, she added, "I get, like, Lindsay Lohan-grade exhaustion, but without any drugs or alcohol. I'm always in bed early, but I'm still tired."

Lawrence was also struck down with illness on the set of her new film, while filming in Boston, Massachusetts earlier this year (15) - and it made for an uncomfortable romance scene.

"I got a stomach virus," she explained. "I was puking and the poor guy - I had to make out with somebody - we were like, spinning and I'd start puking and then I'd do mouthwash and be like, 'Hey, you ready (to kiss)?' Licking my chops like, 'Ugh, let's do it!"'

- WENN