Jessica Simpson silenced her weight critics when she dropped by Good Morning America to show off her amazing, svelte post-baby body.

During the interview, the 33-year-old mom of two revealed how the Weight Watchers program helped her to shed those pregnancy pounds--twice!

"I believe in it with all of my heart," she told GMA anchor Lara Spencer. "It's a lifestyle. I've tried so many different diets, and you can only stick to something for so long. I feel like with Weight Watchers, it just becomes a part of who you are."

Simpson admitted during her first pregnancy with daughter Maxwell, (now 20 months old), she "didn't care" about weight gain.

"I just let myself have whatever I wanted!" she said.

But when she was pregnant with her second child Ace (now 6 months old), she wasn't "as relaxed in my eating.”

"I had already been on Weight Watchers, and I had already lost over 50 pounds," she said. "I was just already in a healthier regimen, so I kept walking and staying active—and Maxwell started walking!"