Mom: Jill's eating addiction will result in a tragic setback

Jaime Pressly's alcoholic character on Mom has a heartbreaking setback in tonight's episode of the CBS comedy—and it's all because of a story line that was created to cover up her real-life pregnancy.

Last fall, executive producer Gemma Baker decided to incorporate Pressly's pregnancy weight gain into a story about Jill (Pressly) becoming a food addict. Now that she's returned from maternity leave (her first episode back was March 1), Pressly has lost the weight but not the urge to indulge. So in tonight's episode, Kristin Chenoweth stars as an effervescent life coach who "cleanses" Jill as a way to break the cycle—but there's no shortcut for addicts, explains Baker.

"It definitely gave us an opportunity to explore a story that we might not have," Baker says of Pressly's pregnancy. "This different solution [to fix addiction] looks positive, but it just isn't the fix."

Jill's battle with food won't end after tonight's episode, adds Baker.

Back in September, Pressly told EW how glad she was that Baker found a creative solution to address her pregnancy—even if it meant wearing a cumbersome fat suit.

"I never figured I would hide behind tables because that never works, and [executive producer] Chuck Lorre is not known for being that cheesy," Pressly said. "I knew they would come up with something fantastic."

Mom airs Thursdays at 9 p.m. ET on CBS.