Exclusive: Jessica Simpson Shares Post-Pregnancy Weight-Loss Plan

Oct. 28, 2013 -- After Jessica Simpson gave birth to her second child, son Ace Knute, with fiancé Eric Johnson last June, she was eager to start losing the baby weight.

"I didn't gain as much weight in my second pregnancy, but I still gained a lot of weight," Simpson, 33, told ABC News exclusively. "Any woman, dealing with their body after pregnancy, you look at yourself and you're like, 'What just happened to me?'"

Simpson, who became a Weight Watchers spokeswoman after the birth of her daughter Maxwell in May 2012, is using the weight-loss program once again, and even credited it with helping her develop a healthier approach to pregnancy the second time around.

Jessica Simpson Introduces Son Ace (See the Photo)

"Going into my second pregnancy, I was just like, 'Oh, I can't eat the whole cake. I can just eat a piece of cake,'" she said with a laugh. "I didn't limit myself, and I definitely was not on a diet during my pregnancy but I did stay active and I had Maxwell to chase around because she turned 1 and started walking, so I was a running pregnant woman."

She said she had been "wanting to feel normal for a very long time -- hormones really can get ya!" she said with a laugh. "Eric has been very tolerant." Simpson has already started watching what she's eating, and she's counting her points.

"An indulgence for me is like, ice cream, so I can have a Skinny Cow for four points, and I know that that'll be the sugar that I want that day," she said. "Today we just had an eight-point lunch, and it was a faux spicy chicken sandwich from Wendy's but it wasn't from Wendy's – we made it in a healthy way."

Go Inside Jessica's Baby Shower

To get more recipe ideas, the fashion mogul reads Weight Watchers' digital magazine, MomFeeds, and even has some tips and tricks of her own. "I love to eat pizza," she said, "And I now eat my pizza on a tortilla."

She also burns calories. Simpson, who said that breastfeeding has been "amazing" though "it's not one of my favorite things in the world," does resistance training with a trainer four days each week and makes sure to log 12,000 steps each day, using a pedometer.

"Eric always goes on a long walk with me," she said. "I really do think as a mom we can get really caught up and not take time for ourselves, and this is a way for me to take time for myself and it definitely makes me a happier mom."

But she's not itching to fit back into her skinny jeans.

"I'm taking it week by week so I don't get frustrated with myself," she said. "If I had a long-term goal, and that's all I thought about it, I think it would set me back more. So I really, every week, try to make sure I stick with my points and get four workouts in. That's my goal this week, and I hope that I can lose from that. If not, I'm going to keep on going and try it the next week. So far, so good.