When "30 Rock" returned for its season premiere and Jenna Maroney (JANE KRAKOWSKI) returned for the new season of "The Girlie Show," the show within the show, the character had gained 40 pounds -- and Jane, who was in terrific shape -- had to don a fat suit.

"I think the storyline came about because I asked [Executive Producer/Writer/Star] TINA FEY if I could do some scenes with CHRIS PARNELL, who plays Dr. Spaceman. I love the way that character thinks, because he is the most wrong doctor in the profession."

Initially, Jenna tries the "Japanese porn star diet," which consists of only eating paper, but you can eat as much paper as you want.

"I did have to eat paper on camera," Jane tells ET. "This is how committed I am to the role of Jenna Maroney."

Then, Dr. Spaceman recommends that Jenna go away to a clinic for a bone shaving and organ reduction surgery. She is tempted, until she sees her fat photo in a tabloid, and realizes her star is on the rise.

Then, Jenna's star takes an even brighter turn when she utters three simple words: "Me want food" at the end of a sketch.

"One of 'The Girlie Show' writers decides that everything should have a food connotation," she says. "Everything is about 'Me want food.' Liz (Fey) is, 'No. We are going to treat her like everybody else. If she were a male, we wouldn't re-write [because of a weight gain]. So, Jenna asks if she can sing and roller dance, and it goes disastrously wrong, because Jenna is not prepared for the weight shift. The only thing that she can think of to salvage it is 'me want food.' It becomes her catch phrase. It is her most famous sketch from that point on. It is the one she is going to have to repeat over and over again."

In real life, Jane says she has never been asked by a producer or casting agent to shed a few pounds.

"I don't like to obsesses about [weight] or let it rule my life," she explains. "I still like to go out to dinner and have a glass of wine here and there. But I keep an eye on it. I do like to exercise. I dance a lot. I do things that are enjoyable and keep stress levels down. I don't like to do tortuous exercise."

"30 Rock" airs tonight at 9 p.m. on NBC.