04/28/2008 at 01:00 AM EDT
Not even getting voted off with her mom in week 3 could derail Ali Vincent from her goal of being the first female Biggest Loser. "She said it from the beginning," says mom Bette-Sue Burkland, who went on to lose 75 lbs. herself. But they didn't know then that NBC's slim-down show would include a week 8 twist that would bring Ali back. Still, says Vincent, 32, "I pictured the confetti falling on my head."
Visualization alone wouldn't do it: In four prior seasons no woman had won. Why? "Maybe women's hormones conspire to hold on to fat for procreation," says the show's doctor, Robert Huizenga. "Women come in with higher body-fat percentage and less fat-burning capability." But that doesn't factor in Vincent's off-the-charts determination. For six weeks before the April 15 finale, the single Mesa, Ariz., hairstylist ate a low-fat diet and ran, swam, hiked and biked up to eight hours a day. "She'll do anything to win," says runner-up Roger Shultz. "I love that about her and I hate that about her!"
Having beat him and 18 others to the $250,000, Vincent says, "I did it! I'm so amazed! That confetti felt like magic." But the best reward may be her killer biceps ("I wear tank tops to cut hair and the arm is moving but no fat is!") and renewed confidence. "I don't know when I forgot I was a strong, capable woman," says the 5'5" former synchronized swimmer. "I awoke the athlete in me. I feel alive again."