"Jacob's character is continually growing throughout the series," Lautner told PEOPLE at the MTV Movie Awards Sunday night, "so I got about eight weeks off before I go back again for Eclipse and I'm going to be hitting the gym."
Lautner, 17, already beefed up considerably for his role as the shape shifting werewolf Jacob Black in New Moon after brief behind-the-scenes debate over whether the role should be recast. He said he'll be getting bigger and bigger "until the end of the series," but he looks forward to returning to his normal size.
"When we're done with the Twilight films I'll definitely bulk down and just get lean again because I don't want to stay big and bulky."
(See photos from the set of New Moon!)
"It's insane!" costar Ashley Greene said of Lautner's new build. "I was going through my phone and looking at all the pictures, and there's one from the wrap party that we did here after the first one and it's incredible. I was like, 'Taylor, did you see this?' He was like, 'Oh my gosh.' He gained 30 lbs. He's not a little kid anymore."
In recent photos from the New Moon set star Robert Pattinson also showed off some impressively chiseled abs, and costar Kellan Lutz said they were achieved without any airbrushed shadows – in fact, Lutz takes some tongue-in-cheek credit for Pattinson's six-pack.
"I've been training him, I've been training Taylor," he insisted straight-faced, but promised that there's no fitness competition among the men of New Moon – at least on his part. "I'm the tallest one and so I'll stick with that trait.
The Italian JobMeanwhile, a handful of the New Moon cast got to shoot scenes on location in Italy, and Greene was one of the lucky ones. "I didn't want to leave. Oh my gosh, I did miss home a bit, but it's so beautiful." She says her co-stars who stayed home resented her "a LOT. When I was like 'Oh, my God, I'm so tired. I'm working so hard.' They were like, 'Shut up. You're in ITALY.' "
Peter Facinelli, who plays the Cullen family patriarch, confirms the dissatisfaction of the non-traveling castmembers. "We were so bummed," he said. "Lazy writing, Stephenie Meyer! LOL. Can you put LOL at the end of that so she doesn't think I'm serious?"