"She did what she had to do," says season 10 winner Patrick House, who once tipped the scales at 424 lbs. and currently weighs 220.
"Rachel's transformation was like any Biggest Loser contestant," says the 6'2" House. "She had to do the best that she possibly could, and at the end of the day, there's a carrot dangling that's a quarter of a million dollars up for grabs."
Season 5 champ Ali Vincent agrees: "I think she chose to win."
"I know what it's like," says the 5'5" Vincent, who weighed 234 lbs. "I gave it every single thing I had. I was working out from 10 in the morning to 2 in the morning. Is that healthy? No! But it's a conscious adult decision to win. I weighed 122 lbs. [at the finale]. I took a drink of water and I gained weight back."
The most upsetting part of the public reaction has been the accusation that Frederickson, 24, suffers from an eating disorder, says season 11 winner Olivia Ward.
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"Granted it's never good to do anything unhealthy to yourself, but let's all support her and give her a couple of weeks," continues the 5'10" Ward, who started Loser at 261 lbs.
"I weighed 132 lbs. when I weighed in. I was up 6 to 7 lbs. in a couple of days, and that was just some basic water weight."
"I'm hoping she will follow her plan to get back to her fighting weight," adds Vincent. "If in a few months she's still exactly where she is right now, then it's our responsibility to get her some help."
Reporting by MELODY CHIU and GABRIELLE OLYA