Jennifer Aniston admits it wasn't easy to lose weight after filming 'Cake'.

The 45-year-old actress ''just didn't work out for two-and-a-half months'' and relaxed her healthy diet to prepare for her role in the upcoming film, in which she portrays a woman who survives a car crash and manages her chronic pain with illegal drugs, but was ready to get back into the gym as soon as shooting wrapped.

She said: ''It's not so easy coming back, let me tell ya! We've got a ways go, but it puts you in a different state of mind not to be physical and not take care of yourself.''

While the former 'Friends' star said she ''loved every second'' of the complex role, she was more than ready to get back to usual routine and diet afterwards.

She told E! News: ''I had to go to a job the day after I wrapped for my hair company and I just sort of had to snap back into businesswoman mode... I was actually ready to let her go, honestly, and felt quite satisfied at the end.''

But Jennifer's co-star costar Camille Guaty admits all of her friends thought the actress, who is engaged to Justin Theroux, was pregnant before she lost weight.

She told UsMagazine.com: ''It's so funny, because a lot of people were like, 'Is she pregnant?' I'd say, 'No,' and they'd say, 'But she looks so dowdy.' I'm like, 'This is the role that she's playing!' Knowing the story, it's just a complete transformation.''