Weigh to go, Jessica Simpson!

Four months after the Fashion Star mentor, 32, welcomed daughter Maxwell (with fiance Eric Johnson, 33), the Texas native is sharing the secrets of her success on Weight Watchers with the new issue of Us Weekly (on stands Friday), featuring stunning outtakes from a recent photo shoot.

"I'm 10 pounds away from my pre-baby size," says Simpson, who got up to 170 pounds while pregnant.

Sharing a typical day in her diet, Simpson says she wakes up at 7 a.m. to feed her little girl, then eats breakfast: half a Flatout flatbread sandwich with egg whites, peppers and fat-free cheddar (6 PointsPlus).

An hour later, Simpson straps on a pedometer and hits the streets with Johnson and Maxwell. "I'm trying to do at least 14,000 steps a day," the singer says. Simpson also exercises four times a week with pro trainer Harley Pasternak. In each 45-minute session, Simpson begins with a cardio warm-up, followed by circuit training that includes dumbbell triceps extensions, hamstring curls and crunches with a medicine ball throw.

"Her waist is going in, and her thighs are getting smaller," Pasternak tells Us of his A-list client. Simpson — who says she makes lunch "her biggest meal" to keep her full throughout the day — will unveil her svelte figure in a series of Weight Watchers ads, debuting September 10.

Now that she's a mom, Simpson tells Us, "I believe I can do anything!"

Source: US Weekly