Researchers followed 14 of the contestants from season 8 of The Biggest Loser, including the winner, Danny Cahill, for six years after the show ended. Thirteen of the 14 regained some of the weight back, and four of those gained back what they had lost – and more.
One contestant, Erinn Egbert, who went from 263 lbs. to about 176 lbs. on the show, was able to keep off the weight and now weighs even less, between 152 lbs. and 157 lbs. But she too struggles with a slow metabolism that burns 552 fewer calories a day than is normal for someone her size.
According to the study, the contestants begin the competition with an average resting metabolism, but as they diet and exercise at a rapid speed to lose enough weight to win, their metabolism significantly slows down, and never recovers.
"It is frightening and amazing," one of the researchers, Dr. Kevin Hall of the National Institute of Diabetes and Digestive and Kidney Diseases, told The New York Times. "I am just blown away."
A representative from The Biggest Loser tells PEOPLE they are looking into the study.
"We have comprehensive procedures and support systems in place which we routinely re-evaluate to ensure all contestants receive the best care possible," they said in a statement. "The lead medical doctor on the show, who has worked with the National Institutes of Health on initiatives in the past relating to The Biggest Loser has been made aware of this most recent study and is in the process of evaluating its findings."
According to the study, published in the journal Obesity, and conducted through the National Institutes of Health, "The Biggest Loser participants with the greatest weight loss at the end of the competition also experienced the greatest slowing of [their metabolism] at that time."
Cahill, for example, went from 430 lbs. to 191 during the show to win. He now weighs 295 lbs., and his metabolism has slowed to the point where he burns 800 calories less a day than he should as a man of his size, according to the New York Times.
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"I swore I would never be there again, be here again. I couldn't imagine a day again that I would weigh over 200 pounds. I feel ashamed. I feel embarrassed. I feel overwhelmed. I feel like failure."
She's now working on losing the weight, and found support from her fans.
"I was spinning. After the news…I looked at my phone and FB and you got me out of bed!"