Jason Segel stopped by the Late Show this week, to talk to David Letterman and to promote his new movie, Bad Teacher, also starring Cameron Diaz and Justin Timberlake.

Jason, who recently lost 30 lbs. explained what motiviated the change.  His assistant came into wake him for work and photographed his appearance which seemed to do the trick. 

“My lowest moment came [when] I shot a movie in New Orleans,” the How I Met Your Mother star told Dave. “New Orleans is like, the best food and booze anywhere … I really took advantage of it.”

So one morning his assistant found him passed out in his hotel room, covered in Taco Bell wrappers.

“She took a bunch of pictures to show me what I had become,” Segel, 31, says with a laugh. “That’s my former stomach.”

 Letterman response: “Honest to God, Jason, this looks like a crime scene!”