The Fashion Star mentor, 31, has been steadily shrinking over the last few months, thanks to the Weight Watchers PointsPlus program and four-times-a-week workout sessions with celebrity trainer Harley Pasternak. And she's eager to show off the results.
"That's a wrap on the @weightwatchers commercial!" the singer tweeted on Thursday afternoon, along with a teaser photo of herself on set, looking super slim in an all-black ensemble and sky-high heels.
Last month, Simpson told Us Weekly she had lost all but 10 of the 70 pounds she gained while pregnant with daughter Maxwell, her first child with fiance Eric Johnson.
"I feel positive about how I've done so far and really good about the goals I have set," she told Us. "Most people can tell a difference every time they see me, which lets me know I'm making progress."