While The Biggest Loser contestants try to lose weight, host Alison Sweeney is packing it on. And no, she's not stuffing her face, lounging on the couch, and ignoring good health rules. She's pregnant.

It's one of the only times in life when it's OK to gain weight, says the 31-year-old Sweeney, who is at peace with the transformation of her body. It's her second time around sporting a baby bump, so she knows what to expect -- and how to proceed with caution.

Cravings: Sweeney has a sweet tooth. Her doctor recommends she eat fruit, which is exactly what she's doing. "I bought a cantaloupe, and I had to stop myself from eating the whole thing. I cut it up and put it in this big bowl and then next thing I knew, half of it was gone," she says.

Working out: She's focusing on her problem areas -- her butt, thighs, arms -- and her workouts include hikes and her costar Bob Harper's spinning class. Every day is different, she says.