Zac Efron underwent ''pretty intense'' training to bulk up for his role in 'The Lucky One'.
The actor plays an American marine in the new film, and had to eat lots of calories and train hard so he could look like a serviceman on screen.
When asked on UK TV show 'Daybreak' if he enjoyed eating lots to put on weight for the movie, he replied: ''That was the good bit, if you like eating fried chicken.
''It was pretty intense. I went thought sort of marine school, I did training and a lot of weight lifting to really look the part.
''I wanted to do the marines justice because these are real American heroes, this is a bit more sensitive than anything I've played before.''
To research the role Zac got the opportunity to meet with marines who had served in Iraq, where his character is posted.
He added: ''I went down to meet several marines with the directors, and really we were just given time to sit with them and ask them questions and find out as much as we could about what it's like to spend a day in the life of a marine. And it was incredibly insightful.''
Zac, 24, has also previously told how he got embarrassed watching the film back with his mother, because of his love scenes with Taylor Schilling.
He said: ''I was kind of squirming. Even though she was a couple of seats down from me, I tried to duck out during those scenes because it was too embarrassing.''