"I've learned a lot about nutrition and how to count my calories" as a result of the show, she told PEOPLE at the second birthday party for pal Nancy O'Dell's daughter, Ashby, over the weekend.
Of course, juggling a diet and exercise routine with two small children and a busy career is tough, but Sweeney says she found a great ally in the EA Sports Active package for the Nintendo Wii.
Not only does it save the Days of Our Lives actress, 32, the trouble of having to find a babysitter, but it is straightforward enough that son Benjamin Edward, 4 ½, can play along as well.
"It's just a good example of how you can really get it done at home," she says. "You don't need to have a big fancy gym membership. One of the things we talk about on The Biggest Loser all the time is just how difficult it is financially to lose weight sometimes. And that isn't an excuse anymore. There are really reasonable options."
Sweeney revealed that she gained less weight with her second pregnancy than with her first, in part by reaching for fresh fruits over processed sweets. She acknowledged, however, that indulging each and every craving is a right of passage for most first-time expectant moms. "You deserve to be spoiled – but within reason," she cautioned.
The More the MerrierLife with two has been twice as nice for Sweeney and husband David Sanov, who have enjoyed the learning curve that comes with a subsequent child. "There is a relaxation of just knowing you’ve been through it, knowing you survived and your kid survives and you can handle it," she notes.
As a result, Megan is an "easygoing" baby who is "ready to rally" at a moments' notice. "Because we're taking Ben to soccer or we're taking him to school or whatever it is," Sweeney explains, "you do kinda relax into it, which was nice. It made me feel like, okay, I got this. I can handle this."
As for Ben, who will graduate from preschool later this month, the role of big brother continues to be greeted with enthusiasm – for now! "Obviously she's not stealing his toys yet or whatever, so I imagine the other shoe will drop," Sweeney said. "But right now he is so loving towards her ... We've been so blessed with that."
Reporting by JESSICA WEDEMEYER