As with the movie that won her an Academy award, Monster, Charlize Theron went method for her latest movie, Tully (which we loved – check out our five star review here).

Tully sees Theron play an overworked mother of three and she gained 50 pounds to play the part, which was even more extensive than her commitment to Monster, she tells Ellen DeGeneres.

While on Ellen’s show, Theron talked about being a parent herself and revealed that her secret to gaining so much weight was eating loads and loads of potato chips – or, as we call them on this side of the pond, crisps.

The actress also discusses the psychological toll of putting on the weight. Overall, it sounds pretty intense.