Jessica Simpson on Surpassing 50 Pound Weight Loss

Jessica Simpson is debuting a brand new commercial for Weight Watchers that reveals her incredible 50 lb+ weight loss after her pregnancy and she spoke to ET about how she was able to get back her pre-baby body. 

"I went over my 50 pound mark, and that day for me was one of the best days I've had in a really long time -- maybe of the year other than having my child -- but yeah, that was a great day," the singer/actress said.

RELATED: Jessica Simpson's Dramatic Weight Transformation

She added: "Our leader Liz gave me the 50 pounds to pick up -- it was in dog food -- and I could barely pick it up. I couldn't believe I was carrying that around on my body. It was amazing."

RELATED: Jessica Simpson Welcomes Baby Girl

Simpson said the dreaded weigh-ins often had her nervous during her dramatic weight loss experience. "There have been moments where my heart has been pounding, like oh my god, oh my god, I hope this is what I am expecting it to be."

Jessica Simpson's New Weight Watchers Commercial

During our interview, she also offers wardrobe tips to women facing similar challenges that are based on her billion dollar fashion empire. "I know people wear a lot of baggy stuff when they don't feel good about themselves. But I say 'belt the baggy' -- it makes you look thinner, I promise you, even if you don't feel that way," she said. "I would show off my legs if I didn't feel so great about my upper body. There are ways to show off what you are proud of," she added.