Kristen Stewart Explains Why Wolfpack Shuns Shirts

Wondering why Taylor Lautner and the rest of his "New Moon" wolfpack never wear shirts?

"They have good reasons," Kristen Stewart, 19, insisted during a Wednesday appearance on the "Today" show.

"They run at 109 degrees... When they [turn into werewolves], their clothes fall off," she went on. "It's not just because they look good with their shirts off!"

Check out photos and video from the "New Moon" premiere!

Stewart was sniffly and sick during her "Today" interview in New York City. The actress premiered "New Moon" (in theaters Friday) last Monday in Los Angeles, and traveled between London, Spain, France and Germany the week before.

"We've been so busy," she admitted. "We've made two movies this year: 'New Moon' and 'Eclipse' and most of the cast worked in between too. It's the coolest opportunity an actor could be given."

Stewart added, "I'm used to doing movies that people don't see... this is once-in-a-lifetime. We make movies for people. I'll never have this."