Hot mama Ashlee Simpson-Wentz is super svelte these days, but she had a lot of baby weight to lose after having her son Bronx.

“I gained 50 pounds, which was awesome!” she told me at Reebok’s fitness event today. “I ate cake and cupcakes. I had a blast!”

While it wasn’t so fun losing the weight she put on, Ash said she had a little extra help with her workout regimen…

She says the secret’s in her Reebok EasyTone shoes, which claim to tone your butt and thighs just by wearing them.

“When I wanted to get back into shape, I worked out and these shoes are amazing because you can really feel them in your booty,” she swore. “But I also worked out and ate healthy.”

Nowadays, she still lifting weight: her growing son. “I carry Bronx, and he’s 33 pounds so I get my workout in,” she laughed.

But  Ash says that she hasn’t quit logging time on the treadmill, adding: ”I try to hit the gym for 30 minutes while Bronx is napping.”

The actress-singer seems to have majorly downsized her work schedule since appearing in Chicago on Broadway, but she’s happy to take a break from her career (along with a recent trip to Hawaii with her hubby and baby). “Being a mom is my first priority and it’s amazing because you grow up and watch your child grow up,” she explained. “It’s the best thing in the whole entire world.”

And even though both Ashlee and sister Jessica have done reality shows, it doesn’t sound like we’ll see ever see the two doing a Simpson sister show.

“I’m a Wentz now, but no,” Ash added. “No plans for a reality show.”