jesssimpsonweightwatchers.jpgJessica Simpson

Jessica Simpson has yet to confirm that she's expecting a second baby, but the songstress did lose 50 pounds from her first pregnancy ... and now she's showing off her bod while shooting a new Weight Watchers ad.

The 32-year-old Fashion Star mentor and fiance Eric Johnson welcomed their daughter Maxwell Drew back in May.

In the new commercial, shot in the California desert a few months ago, Jess says:

    "Weight Watchers changed my relationship with food, and I feel so much more prepared to make the right choices. It feels pretty incredible.”

As for whether her reported second pregnancy will affect her Weight Watchers commitment, time will tell.