06/16/2009 at 01:10 PM EDT
Marissa Jaret Winokur, host of the new weight loss dance show Dance Your Ass Off
, gained baby weight while awaiting the birth
of her son Zev – and she wasn't even pregnant.
A survivor of cervical cancer
, Winokur, 36, had her now-11-month-old son with husband Judah Miller through a surrogate and says she put on 25 pounds during and after the pregnancy. "[It was] total stress," says the actress, who won a Tony in 2003 for the musical Hairspray
. "You don't actually have to carry the baby to gain weight."
Before her son's birth, Winokur got intense exercise while competing on Dancing with the Stars
last spring. "During Dancing
, I was working out all the time." But the strain of motherhood soon took its toll. "When I wasn't working, if I had an hour [and] my husband wasn't home from work yet, I'd be like, 'Oh, I'm gonna run on the treadmill.' [But sometimes] you have an hour and the last thing you wanna do is get on a treadmill."
Winokur is back on her fitness routine, thanks to classes at Studio City's Cardio Barre. Ironically, though she considers her new show a combination between The Biggest Loser
(it premieres on Oxygen June 29th), it wasn't much help to her. "I hosted the whole season and didn't lose a pound. I'm like, 'Oh my God, this is insane,' " she says.