Jessica Simpson showed off her slim figure in a curve-hugging black dress for a new Weight Watchers commercial. The 33-year-old proudly flaunted her toned body after dropping pounds since giving birth to her second child, Ace.

In an interview with "Good Morning America," Simpson opened up about her struggles to lose weight following her two pregnancies.

"I was so insecure - I couldn't even believe what I weighed," she said.

After giving birth to her daughter, Maxwell, the fashion designer and singer shed 50 pounds but five months later announced that she was expecting another child with fiancé Eric Johnson. She gave birth to her son, Ace Knute, 7 months ago.

"I don't think that I ever expected myself to see the numbers that I have seen on the scale," Simpson said referring to her weight after she had her second child.

Simpson was criticized for her weight gain but was determined to stay about positive telling "GMA" that she doesn't think women should be afraid to gain weight when pregnant.

"You are creating a life, and honestly it's not easy," she said. "It is a really hard thing to go through. And you deserve to eat your ice cream, you deserve to have your pancakes. Do whatever you want to do and then afterwards just know that you have to work really hard."

"I had to learn that with my first and second pregnancy," she added. "My first pregnancy I ate a lot more, but my second pregnancy I ate enough, like I ate what I wanted to eat but I stayed active and I think because I had gained so much weight with my first that I had to stay active throughout my second because I didn't know what to do with myself if I didn't."

She explained that she followed a diet plan and starting choosing healthier options.

"For breakfast I am an oatmeal girl," she said. "Lunch, I do like bread so I will have a sandwich or something. But for dinner I try [to] keep it super clean."