Eve said that it was hard to maintain a spinach diet but she had to do it in order to slip into her spacesuit, reported Radar Online.
"You've got to look as if you can hold your own on the Enterprise, and that means you've got to be in proper fighting shape," she said.
The 31-year-old explained that she started a diet a week after she learned that she nabbed the role.
Eve, who is featured in her under garments in promo shots for the film, isn't the only Hollywood star who has lost a lot of weight for a role.