She did it once and she can do it again!

Jessica Simpson appears on the January/February 2013 issue of Weight Watchers magazine. Wearing a star print top and black pants, the singer proudly shows off her 50-pound weight loss after the May 1 arrival of her first child, daughter Maxwell. (Simpson wore the same outfit during a Macy's appearance in Costa Mesa, Calif., Nov. 10.)

In the accompanying interview, the Texas native, 32, reveals how she stayed fit while taping the second season of NBC's Fashion Star. "I'm crazy about smoothies, so I bring fruit chopped up and ready to go. That way, I can sip the same smoothie all morning long between takes," Simpson shares. "If it thins out, I put it back in the blender with crushed ice for a few minutes."

As Us Weekly exclusively reported in its Dec. 10 issue, Simpson is currently pregnant with her second child. (Eric Johnson's fiancee of two years waited until Christmas to share the news with fans via Twitter.)

The once-wed star addressed her baby news in a just-released commercial for Weight Watchers. "This year is all about new beginnings for me," Simpson says in the ad. "I lost over 50 pounds on Weight Watchers and did not have to be perfect to do it. Being healthy has become a part of who I am -- which is great timing, because I'm having another baby."

(A rep for Weight Watchers tells ABC News Simpson "will not be following the program during the pregnancy while her weight and well-being are monitored by her obstetrician, as is recommended for any woman during pregnancy. After she gives birth, Jessica and her doctor will decide when she may resume following the Weight Watchers program.")

Says the pregnant fashion designer, "I feel like I'm on top of the world!"

This article originally appeared on Usmagazine.com: Jessica Simpson Shows Off 50-Pound Weight Loss on Weight Watchers Magazine Cover