What happens when you go from struggling actor to global superstar? Does the attention, adulation and money change you after a star turn in a $380 million worldwide box-office smash like "Twilight"? Not if you're Robert Pattinson, Kristen Stewart or Taylor Lautner, according to co-star Kellan Lutz.

"Rob is still just as awkward!" Lutz told MTV News at the Chicago stop of the "New Moon" Hot Topic promo tour. "He's such a shy guy. He has a lot of weight on his shoulders, a lot of responsibility as the actor to carry these films, and he's still the same goofy Rob.

"It's really cool to be a part of a project where everyone's still the same," continued Lutz, who plays vampire Emmett Cullen. "I think that maybe Rob or Kristen, or especially Taylor -- he's kind of younger and this is so huge to be thrown into the limelight -- but everyone is still the same person. It's really cool to be part of such a strong, down-to-earth group of actors who are talented and humble and thankful."

While Lautner may not have changed as a person, his physical transformation has been undeniable as he [article id="1625920"]packed on muscle to keep the role of Jacob Black[/article] for "New Moon." In this respect, Lutz could not be more proud of his co-star. "I got to hand it to him," Lutz said. "He was a kid when I met him and worked with him on 'Twilight,' and he turned into a man so quick. He had a growth spurt; he's growing some facial hair. He bulked up, and he really won the role, gained 30 pounds. It's not like the studio paid him to work out or paid him to gain the weight. He actually took it under his own initiative, and his dad's amazing and kept him on a track."

In "Twilight," Lutz was the bulkiest dude in the cast. What happens now that he isn't the only muscle-bound guy on set? Any good-natured jealously between Lutz and Lautner?

"I'm the tallest one, so I don't worry about size," he said with a laugh. "I'll always have the height."

MTV delves deep into the "Twilight" universe with two can't-miss specials: "Love Bites" chronicles the budding rumored romance between Robert Pattinson and Kristen Stewart on Monday at 10 p.m. ET/PT, while "New Moon Revealed" will feature die-hard fans as they gather to meet the saga's stars Monday at 10:30 p.m. ET/PT.

Check out everything we've got on "The Twilight Saga: New Moon."

For young Hollywood news, fashion and "Twilight" updates around the clock, visit HollywoodCrush.MTV.com.