In 2008, Ali Vincent became the first woman to win the Biggest Loser after dropping 112 pounds. But last month, just four days after the anniversary of her win, Vincent revealed she's gained most of that weight back.

The former contestant took to Facebook to share her story, starting with her recent decision to join Weight Watchers — "one of the hardest things in my life," she wrote. She swore to herself that she would never weigh over 200 pounds again; she started The Biggest Loser at 234 lbs. But, she added, stress and "nightmares I wouldn’t wish on an enemy" got the best of her. And when she appeared on OWN for an episode of "Where Are They Now?" she said she was too ashamed and embarrassed to tell other people.

She's not alone. Several studies have shown that people who lose weight over a short period of time often gain it right back. One study by researchers at the University of California at Los Angeles combed through 31 long-term diet studies and found that at least one-third to two-thirds of people on diets regain their weight, or more, within four or five years.

Vincent first expressed her fears about maintaining her weight loss shortly after her 2008 win on Oprah Winfrey’s now-defunct talk show. Already, she admitted, she had been tempted by her old lifestyle.

"I got home and I was like, 'what do I do? What do I do without the ranch?'" she told Winfrey eight years ago. "I went out, I partied with my friends. I woke up and I was just like, 'this isn't me. I don't want this life anymore.'"

Today, Vincent is determined to get back on track, humbled so far by the support of her friends and family. This time, though, it's less about hitting a specific number on the scale and more about feeling and being her best self.

"I want to love myself at any size, and throughout the sizes," she said.