"I gained, I think, 65 pounds when I was pregnant," the 32-year-old mother and "Wipeout" host said. "And I will say to moms out there, 'Don't stress about losing it. It will happen when it happens.'"
Lachey credited her ability to lose weight to her healthy lifestyle.
"Cam's 9 months, so it's been a minute, and we're working, and we're traveling, and it's just about maintaining a happy, healthy lifestyle, not obsessing about it," she said.
"It's not about this 'get skinny quick' diet or these fads. Just enjoy time being a mom. You've just had this wonderful, magical moment, and you shouldn't be stressing about that kind of stuff."
But there's no shame in a little help either.
"Spanx are amazing," Lachey quipped. "Thank you to the inventor of that."