The actress posted the image yesterday alongside the caption "New Year New Me". She went onto explain through a series of hashtags that her radical transformation, complete with a stubbly beard and strawberry blonde hair, was for a role for a film that was never made.
"#makeupbyrickbakerin2011 #themovieneverhappened😢 #turnsoutiwaspreggers #babiesarebetterthanmovies #happynewyear❤️" read the caption.
The star was in fact expecting her third child with then husband, Ben Affleck.
Social media users quickly commented underneath the picture, noting the similarities to male actors including James Franco, Ryan Reynolds and Eddie Redmayne. The image has so far received nearly 30,000 likes.