VIDEO Jillian Michaels on Biggest Loser winner Rachel Frederickson’s dramatic weight loss

Jillian Michaels thinks Biggest Loser producers should have warned trainers about contestant Rachel Frederickson’s weight loss before the live finale.

“Nobody told me like, ‘Oh hey, Rachel is very, very thin.’ Bob [Harper] and I had no idea,” Jillian said during a Skype interview with HuffPost Live on Thursday. “Nobody had told us. Nobody had said anything to us. So yes, I was stunned. Obviously I thought she had lost too much weight.”

During the Feb. 4 finale, Jillian and Bob were visibly shocked during Rachel’s introduction. Expert lip readers noted Jillian mouthed “Oh my God” several times.

Jillian, who has trained dozens of contestants throughout the years, told HuffPo Live she was “immediately concerned” for Rachel’s health.

“In my opinion, this had fallen through those checks and balances,” she said of Rachel, who lost 155 lbs. throughout the course of the show. By the finale, Rachel’s BMI was classified as “underweight” by the National Institutes of Health.

Rachel, who later admitted she was “too enthusiastic” about her diet and exercise regimen, looked healthier during a Today appearance on Wednesday. Still, she maintained she went about the whole process in a healthy manner.

“I was [surprised], because I felt proud of everything I’d accomplished. My journey was my own, and I loved it; I lived it. So, I felt really proud of what I did.”

Jillian seemed unconvinced, telling HuffPost Live it isn’t good to become obsessive.

“Anybody who gains too much weight or loses too much weight, ironically these are manifestations of the same issue. It simply means that somebody is utilizing their relationship with food to manage emotions that are painful, hard, difficult to face or control.”