Jessica Simpson has been working hard to lose weight after her second pregnancy and the determination has really paid off.

The 33-year-old singer flaunted her svelte figure Sunday in a spring-honoring canary yellow dress and white high heels while attending the John Varvatos Stuart House Benefit in West Hollywood.

The singer began her weight-loss journey by signing an endorsement deal with Weight Watchers in 2012 during her first pregnancy with her daughter, Maxwell.

She quickly became pregnant with her son, Ace, and had to curtail her weight loss until after the delivery.

But, once she was given the green light, she was on her way with the help of Weight Watchers.

We are obsessed! @JessicaSimpson turned heads in this little yellow number over the weekend: http://t.co/AgFbzxX9Xq pic.twitter.com/ATkDZ0mHGI

— Us Weekly (@usweekly) April 14, 2014

After several months of hard work, Simpson showed off a 70-pound weight loss in a Weight Watchers ad.

“This body made two amazing little human beings. I love this body and what it’s capable of — no matter what size,” she said in the ad. “But this version feels really good.”

Simpson has been careful with her methods, opting to go slowly and avoid any fad diets or quick-fixes. “I really do feel this need to be the best role model for my children,” she said in a Good Morning America interview in January. “I want [Maxwell] to look up to me and want to be like me…I don’t want to give her any false perception of what is real and what’s important.”

Slipping back into that #LBD = a great weight loss milestone!!! RT @JessicaSimpson Too proud to sit down!! pic.twitter.com/7paihlvKU7

— Weight Watchers (@WeightWatchers) February 10, 2014

Jessica Simpson saw weight loss results "really quickly" after having baby #2! http://t.co/OND38zqXuG pic.twitter.com/VkZA6UzCO6

— Us Weekly (@usweekly) December 16, 2013

How INCREDIBLE does @JessicaSimpson look? Just saying. http://t.co/xyOdjcWlvq pic.twitter.com/wWEUPnZiQl

— OK! Magazine (@OK_Magazine) March 8, 2014

Image via Wikimedia Commons