If you followed the arc of "Mad Men" actress January Jones' real-life pregnancy, you know that the slim TV star never looked ... that big. And by that big we mean the really full-figured look Jones' character, Betty Draper
, showed off during Sunday night's second episode of the show's fifth season.

That Betty was, well, big all over: in the face, the arms, middle. And while we still don't know the identity of Jones' real-life baby daddy, one mystery was solved on Monday when it was revealed that Jones was wearing a fat suit and prosthetic face and neck appliances to make her character look heavy duty.

While Jones was pregnant with her now-six-month-old son Xander during filming, instead of writing that into the plot, series creator Matthew Weiner had the series' writers explain it away by explaining that Betty had packed on the pounds out of boredom, depression and a distance from her second husband, Henry Francis.

The shocking makeover divided fans and once again caused the kind of Monday morning quarterbacking that TV execs salivate over, which was totally the point. According to the Hollywood Reporter the makeup artists on the show did the same thing for Jones that they did for castmate Elizabeth Moss when her character Peggy Olsen was pregnant during season one. The crack team covered Jones in a fat suit and prosthetic facial and neck appliances that gave Betty a surprisingly zaftig look. In addition, they used a back double for the scene where Betty steps out of the shower.

While Jones' Betty has a history of weight issues stemming from a childhood as a chubby kid whose every meal was monitored by her mother, only to shed that weight to become a slender model, the Reporter speculated that her emotional eating may have been triggered by her ex Don Draper's sexy, slim new wife, Megan.

Jones gave birth to Xander in September and was quickly back to her old shape, thanks, in part, she claimed, to such unconventional methods as eating her own placenta. "It's not witch-crafty or anything. It's something I was very hesitant about," she told People magazine at the time of eating the lining of her uterus in dehydrated pill form. "But we're only the only mammals who don't ingest our own placentas."