Jessica Simpson Shows Off 50-Pound Weight Loss in Weight Watchers Ad

Looking good, Jess!

She's got one of Hollywood's most talked-about bodies, and Jessica Simpson proudly showed it off while shooting a Weight Watchers ad in the California desert a couple months back. After giving birth to her first child, daughter Maxwell Drew Johnson, in May, the designer, singer and "Fashion Star" mentor, 32, successfully dropped 50 pounds on Weight Watchers.

PHOTOS: Jessica's body evolution

In an outtake from the "Expect Amazing" campaign (which begins airing on Dec. 25), the famous blonde looks radiant and slim in tight jeans, boots, low-cut black tank top and plaid shirt. "Weight Watchers changed my relationship with food, and I feel so much more prepared to make the right choices," says the spokeswoman. "It feels pretty incredible."

PHOTOS: Jessica's first pregnancy with Maxwell

Of course, the star (who dropped the weight by sticking to her Weight Watchers points and four trainer sessions a week) is set to undergo another transformation: As reported exclusively by Us Weekly, Simpson is now pregnant with her second child.

"Jessica loves being a mom," an insider told Us. "She really is overjoyed."

PHOTOS: Meet Maxwell Drew Johnson!

(Simpson's rep had no comment regarding the second pregnancy.)

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Jessica Simpson steps out in L.A. with fiance Eric Johnson and daughter Maxwell