Jessica Simpson is taking her post-baby weight loss efforts seriously -- and it's paying off, big time.  On Sunday, the mom to Maxwell headed to LAX to catch a flight to NYC.

Last week, Simpson opened up to Us Weekly about her success using Weight Watchers so far.  "I'm 10 pounds away from my pre-baby size," said the singer/designer, who got up to 170 pounds while pregnant.

In addition to adhering to the popular point-based eating plan, Simpson said she's working out four times a week with celeb trainer Harley Pasternak.

Good for her, she looks great!

~Vanessa