Trista Sutter can easily run through all the ways in which her second pregnancy was different from her first. For starters, "your body just knows where the fat goes!" she says. Then there was having to squeeze in gym workouts around her 2-year-old son Max's schedule, not to mention "just being exhausted." By the time daughter Blakesley Grace arrived in April, the 5'2" Sutter had gained 43 lbs., to get her to 153 lbs. "I saw that number," she says, "and was like, 'Oh, God—how am I going to lose it?'" The answer: lots and lots of exercise, including daily 45-minute walks with the kids (pushing 70 lbs. uphill in a double stroller), as well as strength routines with a personal trainer three times a week. And while Sutter didn't avoid any foods, she kept rigorous track of her portions with the Web site mycalorienumber.com (which provides menus and grocery lists), to keep her caloric intake to 1,750 a day. Now, at 107 lbs., "my stomach is still a little poochy," she says. "But I am proud of myself!"