Dr. Jennifer Kerns is a Biggest Loser contestant turned obesity specialist.

She co-authored a study with the National Institutes of Health in 2016 that found most Biggest Loser contestants' metabolisms slowed. The show went off the air later that year.

Kerns told Insider she's not sure the new show will do the weight loss process justice.

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By The Biggest Loser's standards, Dr. Jennifer Kerns was an unusual contestant. She was a doctor who, in 2006, appeared on the show's third season, alongside the other 49 contestants. Then she came back, appearing in the next two seasons as a medical consultant. Her presence served as proof that the show worked: if she lost the weight, so could her successors.

Kerns' backstory was perfect fodder for the show. She was morbidly obese as a child, and 300 pounds in college. She tried to lose weight many times, trying everything from "fat camp" to Weight Watchers, but she'd always gain it back.

Something changed for Kerns while she was in medical school at George Washington University.

She and her classmates watched porn featuring of all kinds of people, from same-sex couples to disabled couples, in an effort to get more comfortable seeing different kinds of potential future patients (a not-uncommon practice in medical schools). But while watching porn of an obese couple having sex, Kerns saw a classmate in front of her scoff.

"I thought, 'My God, really? Like, it's okay to see people in wheelchairs having sex. It's okay to see same-sex couples. But fat person having sex is disgusting?'" Kerns told Insider.

Worried that patients wouldn't take her seriously as an obese doctor, she applied for The Biggest Loser, and became a success story.

Kerns published a controversial study on former contestants of The Biggest Loser that found their metabolisms slowed

In 2016 she co-wrote a controversial study, funded by the National Institute of Health, studying 14 former contestants on The Biggest Loser, 13 of whom had regained some or most of the weight.

The study showed that in the years since the show, contestants' metabolisms slowed until they had to eat far less than a typical person of their size and height, just to maintain their current weight.

When the study came out, many saw it as a death knell for the show, which went off the air later that year.

Jennifer Kerns as a contestant on The Biggest Loser Season 3 NBC/Getty But Kerns maintains the timing was a coincidence, and insists that the study was not a "take down" of the show.

While there was a "definite slowing of metabolic rate," Kerns told Insider, "it wasn't unique to The Biggest Loser." Having to work twice as hard to keep the weight off is a dilemma anyone struggling to lose enormous amounts of weight will face.

In fact, Biggest Loser contestants did better than the subjects of the gold standard of clinical weight loss trials, the Look AHEAD trial, losing on average 12% of their body weight.

There's another study Kerns pointed to, which used people from the National Weight Control Registry, a database of people who lost weight in far slower, and far less dramatic ways than the Biggest Loser contestants. Both studies seem to support what Kerns' study showed: that losing weight might be twice as hard as it would be for a thin person, but it isn't high-risk.

The series helped to show that obesity doesn't equal laziness — but it also made skinny the goal

The Biggest Loser format is simple. Take a bunch of contestants, put them on a secluded ranch for four months, removing them from the trials and tribulations of the outside world, and encourage rapid weight loss through endless workouts, highly restrictive eating, and televised weigh-ins.

The new season looks like it will follow this format, with some adjustments. The focus will be more holistic, with individualized meal plans for each contestant, doctors on set to monitor workouts, with less of an emphasis on weight loss and more of an emphasis on overall health. Nonetheless, Kerns has her doubts the show has really changed.

"They're in this secluded bubble from the rest of the world and there isn't a lot of teaching on how to break habit cycles," she said.

The season 3 finale of The Biggest Loser, which Dr. Jennifer Kerns competed on. NBC/Getty Season 2 contestants Jen Watts told the New York Post that when she left the show, "I thought, 'I can't work eight hours a day because I have to train eight hours a day.'"

Kerns, who hasn't been asked to consult on the revamped version, has "really mixed feelings" on it. For obese people who've given up on health, she says the show can provide a dose of hope.

"I think it at least showed other people who are struggling with obesity that all is not lost, that they can successfully lose weight even if they have 150 pounds to lose," Kerns told Insider. "It showed people with obesity are not lazy and that they can work very hard."

But that portrayal could also be harmful. As long as an obese person was working on losing weight, they were worthy of appreciation. No other accomplishment seemed to matter as much as the number on the scale.

The format of the Biggest Loser is a problem, Kerns says

But Kerns' main problem with the show has to do with the structure of reality television itself. "To make a good TV show, they're going to want to show rapid change," said Kerns.

Making contestants run a race with doughnuts they weren't allowed to eat in their mouths (one of the challenges in the show) makes for good, if degrading, television, says Kerns. Showing slow, steady, sustainable weight loss isn't good television.

Bob Harper, the new host of the show, says the reboot will be more empathetic. Kerns isn't sure that's possible on TV. Tyler Golden/NBC/NBCU Photo Bank via Getty Weight gain is the result of a deeply ingrained habit loop

Kerns began the show at 270 pounds and ended at 162. For her, food was a coping mechanism. Feeling bad meant wanting to eat food that triggered dopamine in her brain, which would then make her feel better. That would condition her mind to know that eating food led to feeling better. It is that conditioning teaches people to eat food like sugar when they feel bad.

There are many biological reasons why people become obese, a topic, Kerns says, that is not explored in the show.

"We have brain mechanisms from thousands and thousands of years of evolution that want us to eat caloric food," said Kerns. "And some of us learned that those brain mechanisms that used to keep us alive are now hijacking how we feel and using food to make us feel better when we're upset." And these habits are very, very hard to change. That's why even people who have weight loss surgery might end up regaining the weight.

There is no easy solution, contrary to what The Biggest Loser says. "We have to address the neuroscience and what's triggering us to overeat and I don't think any TV show could really do it justice," says Kerns.

Kerns' hope for the new season is that they won't just teach the contestants to white-knuckle their way through weight loss. "I hope it's not a very food focused effort where it's 'eat this, don't eat that.' My hope would be that the new version of the show would be heavier on mindfulness and psychology. But I somehow don't think they're going to be able to get into it in the way that I would hope."

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