The 32-year-old actor is paired opposite actress Emily Blunt in the film and he said that in order to look good as a couple he was asked to lose weight, reported Us magazine.
"The studio president told me that it had to be conceivable that Emily Blunt would ever choose me to be her husband. Which is fair," Segel said.
The 'How I Met Your Mother' star is also the writer of the film and specifically wrote the role of his wife for Blunt, 29.
And even though he's good friends with the actress and her husband, John Krasinski, he didn't mind shooting the love scenes.
