Los Angeles voice-over artist Rachel Fredrickson won season 15 of NBC's "The Biggest Loser" Tuesday night, shedding 59.62 percent of her body weight to drop from 260 to 105 pounds, prompting hand-wringing on Twitter.

"She looks anorexic and this was the reaction of the trainers," one person wrote, attaching a screen image of Jillian Michaels and Bob Harper appearing to look concerned at the drastic change.

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"So disturbed. Never thought [the show] could be so frightening," wrote another.

Dietitians and nutritionists who spoke with CBS News, however, were divided over whether her 7 1/2-month weight loss was unhealthy.