The Parks and Recreation funnyman, who plays a member of Navy SEAL Team 6, which was responsible for capturing and then killing Osama Bin Laden, transformed his body into a massive bulk of shredded muscle.
Just take a look at the photo Pratt shared of himself during his appearance last night on Conan. The very revealing pic shows him wearing nothing but a pair of white boxer briefs while flexing in the mirror of a hotel bathroom.
"I was about 50 pounds or 40 pounds lighter than I am now," Pratt told us at Zero Dark Thirty's recent Hollywood premiere. "I worked out really hard and I cut out everything bad for me for a long time and I just focused on trying to become a believable Navy SEAL."
"I got to meet some of these guys through the course of making this movie," he continued. "It was just important for me not to embarrass them, you know, to create a character that was somewhat believable as a SEAL."
Pratt, who is married to funny lady Anna Faris (she gave birth to their first baby, Jack, almost four months ago), has since put on 60 pounds to play what he calls a "fat and unhappy" character in another movie.
Here's hoping he plays a Navy SEAL again one day.