updated 04/21/2008 AT 01:00 AM EDT
•originally published 04/21/2008 AT 01:00 AM EDT
'I USED TO BE OVERWEIGHT!'
The 5'2" trainer says she's deliberately tough on the Loser contestants—because that approach worked for her. After reaching 170 lbs. by age 14, she joined a martial arts class where "my teacher would kick me," recalls Michaels, 33. "I would cry—and he would kick me harder until I stopped crying." Those daily workouts combined with trading pizza for low-cal Greek food got her into perfect shape—well, almost. "There is one cellulite dimple that I named, like, 'Look at Delores, she's huge today,'" she says. "I'm a work in progress."
"So many people think I'm just genetically fit," says Lyons, 34. Her response? To show pictures from her college days. "In college I gained probably about 5 or 10 lbs. every year," she says. But after hitting a high of 145 lbs., the 5'3" Lyons began working out with a trainer and cutting back on sugary drinks and food—and still calls on that experience when training clients. "I don't know what it's like to be 100 lbs. overweight," she says. "But I can tell you how crappy I felt being 30 lbs. overweight."