"I told [director] Darren [Aronofsky], I was like, 'First you got me skinny, and now you're getting my fat,' because he introduced me to my fiancé," the actress, 29, tells Extra. "It's the greatest gift he ever gave me."
Portman, who is expecting her first child with her choreographer fiancé Benjamin Millepied, is slowing down her schedule – but that's not easy, given that she's an Oscar front-runner heading into Hollywood's awards season.
"I'm just doing these events, and then I'm going to try to take it easy," she said at this weekend's Palm Springs International Film Festival.
Her red-carpet fashions will have to change, of course – but her home attire is already super casual. "I just want to be in things that are comfortable now – loose!" she says. "I wear sweatpants on a daily basis."