“It’s total b——-,” Michaels tells PEOPLE at an event for Krave Jerky. “It’s complete b——-.”
“What I can tell you, simply, is that eating right and working out will never, ever, f— with your diet.”
The study, conducted by researchers from the National Institutes of Health and published in the journal Obesity, tracked 14 contestants from season 8 of The Biggest Loser for six years after the show ended. Thirteen of the 14 regained some of the weight, four of whom gained back that and more, while one lost additional weight.
A representative from the show told PEOPLE that they were looking into the study further.
Michaels, 42, who got her start in the fitness world through her popular line of exercise DVDs, before joining The Biggest Loser as a trainer when the show debuted in 2004, says she also has a critical eye on the fast-rising Instagram fitness stars.
“I kind of look at fitness in three generations,” she says. “So there’s the TV generation, the YouTube generation, like the Tone It Up girls, and Cassey Ho, and then you’ve got the Instagram generation. Some of them are amazing, I think that Amanda Bisk is a badass, her body is insane, she’s got a degree in exercise physiology. Her? All day long. The ones that have never trained anyone a day in their life, that just wear a bikini and take photos of themselves, and have gluteal implants and sell an ebook for $150 telling you they’re going to give you that ass? I mean, come on.”
RELATED VIDEO: America’s Toughest Trainer Jillian Michaels Has Some Healthy Meal Tips for Parents and Their Kids“But like anything, there are great people in every business, and I think Instagram has some incredible talent on there and it has some crap talent on there, just like TV, just like YouTube. But the cream always rises to the top.”
As for Michaels, she thinks she’d never make it as an Instagram star, but she’s excited about the possibilities for women.
“When it’s like, ‘Look at me in my bikini,’ I’m thinking good for them, but I’m also very surprised that women want to look at another woman in her bikini,” Michaels says. “My generation, they attack that. It’s a very different thing. So it would have never been a possibility, I would’ve been shamed and attacked, so I kind of love that it doesn’t happen, I kind of love that women are being celebrated for that.”