Experts cautioned that regardless of her current weight, the criticism being levied on social media about her losing too much isn't helpful. A more constructive message is needed, they say, centering on overall healthy living and body image.
The 5-foot-4, 24-year-old Frederickson dropped from 260 pounds to 105 under the show's rigorous exercise and diet regimen, and time spent on her own before the finale. She was a three-time state champion swimmer at Stillwater Area High School in Minnesota, then turned to sweets for solace after a failed romance with a foreign exchange student she followed to his native Germany.
Frederickson's newly thin frame lit up Twitter on Wednesday, with many viewers pointing to the surprised expressions on the faces of trainers Jillian Michaels and Bob Harper during the show's Tuesday night finale. Many tweeted that Fredrickson looked anorexic and unhealthy, while others congratulated her for dropping 155 pounds.
Jillian Lampert, senior director of the Emily Program, an eating disorder treatment program based in St. Paul, said Frederickson's body mass index is below the normal range. But she said the criticism directed against her isn't helpful.
"As a society we often criticize people for being at higher weights - that's part of why we have the TV show 'The Biggest Loser' - and then we feel free to criticize lower weight," Lampert said.
A more constructive message to send young people would center on well-rounded health and the importance of eating well, moving well and sleeping well, she said.
"We certainly see a lot of people who struggle with eating disorders who use the same behaviors on that show to an extreme," she said. "That can't be helpful."
Joanne Ikeda, a dietitian and retired faculty member at the University of California at Berkeley's Department of Nutritional Sciences, added that focus needs to be on embracing body-size diversity.
"We are just obsessed with body size, women particularly. There's just tremendous body dissatisfaction," Ikeda said. "I'm sure even if she was the exact right size, someone wouldn't like the look of her fingers or the length of her hair."
"We should be happy we don't all look like Barbie and Ken," she said.
A listed phone number for Frederickson couldn't be found by The Associated Press late Wednesday. During an appearance on "Access Hollywood," Frederickson didn't directly respond to the criticism but said she intends to live a healthy lifestyle going forward.
"My journey was about finding that confident girl again. Little by little, challenge by challenge, that athlete came out. And it sparked inside me this feeling that I can do anything I can conceive. And I found that girl, and I'm just going to embrace her fully," she said.
In a statement released late Wednesday, NBC said the network is committed to helping all of the show's past contestants live healthier lives.
Among the social media commentators was 36-year-old Shannon Hurd, who tweeted that Frederickson looked weak and unhealthy. In an interview Wednesday with AP, Hurd said she became anorexic at age 16 and has been recovering since she was 19.
"Looking at her 'after' photo, I guess I saw ... a piece of myself way back when, and it really just struck something deep down," Hurd said from her home in suburban Denver. "I don't know if she's anorexic, but I do think her weight loss is so extreme there is no way her loss can be maintained through normal habits, and unfortunately that leads to distorted thinking."