The previous day, Dec. 2, Jess was snapped looking just as sexy in a chic but slightly less casual ensemble. Leaving an office building in Manhattan, the former Fashion Star mentor looked nearly red carpet ready in a head-to-toe black ensemble and sky-high boots!

And in November, just five months after giving birth to her son Ace, Jess was back in a swimsuit! Her stylist Nicole Chavez Instagrammed a pic of the yummy mummy's white one-piece, which she wore the set of a Jessica Simpson Collection fashion shoot.

The fashionista and working mom got back to her bathing suit bod after giving birth thanks largely in part to her Weight Watchers diet. She has an endorsement deal with the program, which encourages healthy, mindful eating to shed pounds in lieu of fad or crash diets.

Clearly, it's working for Jess!