Obesity: Personal responsibility or genetic destiny? Here's what the science says

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The Biggest Loser triggered fad diets across the world. But most of the US contestants regained the weight they lost on the show. Why? And what does this mean for the rest of us?

Watch the 12-minute documentary above.

In 2014, Katrina was one of four finalists on Channel Ten’s The Biggest Loser.

“I actually didn't apply for the show myself. My husband put my name forward. But I thought maybe this will be the last time that I have to try and lose weight and my life will be perfect,” says Katrina.

Over the course of the series, she lost 43.8kg. But in the years since she has regained most of that weight.

“I feel like I’ve failed because I haven’t been able to keep that off.”

“After being on the Biggest Loser my diet really didn’t get out of control. The exercise didn't stop and yet weight was coming back,” says Katrina.

A 2016 study of Biggest Loser contestants in the US found that most regained the weight they lost on the show.

“That is a body defence mechanism,” explains Sydney bariatric surgeon Dr Brendan Ryan.

“The body has seen and perceived you as going through acute starvation, so it puts the breaks on your metabolism, it slows everything down to protect you, so you don't die.”

“But the problem is that not only do you stop losing weight but, when you stop that intense program, the metabolic rate stays low and you regain all that weight,” says Dr Ryan.

Some argue that diet and exercise are not only ineffective but also harmful.

Danielle Galvin is a 27-year-old body positive activist and Instagrammer from Cairns.

“I’m 100% anti-diet. I eat what I want, when I want,” says Galvin.

At the age of 11, Galvin started going to the gym to try to lose weight. “As much weight as I lost I always seemed to gain it back. When that happened I just found myself restricting more and exercising more and before I knew it, it wasn’t something I could control.”

“I was probably exercising six hours a day and I wasn’t really eating,” says Galvin.

In her late teens Galvin finally sought help.

“After recovering from my eating disorder I slowly came to terms with the fact that if I was going to be happy perhaps I would be a fat person.”

“You can be fat and healthy. And you don’t have to conform to the beauty standards or the health standards that I think are quite biased,” says Galvin.

Professor John Dixon from the Baker Heart and Diabetes Institute in Melbourne describes obesity as “the biggest epidemic the world has ever seen”. But Professor Dixon believes we need to fundamentally change the way we think about obesity and how to treat it.

We've got no right with our current knowledge to blame anyone who has a weight problem.

“We've got no right with our current knowledge to blame anyone who has a weight problem. Your weight and how it’s going to change through life is set in the first thousand days after conception,” says Dixon.

“It's what happened to some extent in the genes they were given and how they were programmed for the first thousand days of life,” he says.

Professor Dixon says that diet and exercise programs are ineffective at combatting obesity when compared to bariatric – or weight loss – surgery.

“Lifestyle treatments – diet and exercise – produce maybe one to 4% weight loss and it's very hard to sustain over time.” 

“People who have bariatric surgery generally lose 20-30% weight on average and the vast majority will lose more than 10%. And of course it treats their weight-related diseases such as diabetes, heart disease,” says Dixon.

Dr Brendan Ryan does more than 500 bariatric surgeries a year.  One of his patients is Sydney woman Amelia Blaze.

For my 30th birthday I purchased a vertical sleeve gastrectomy.

“For my 30th birthday I purchased a vertical sleeve gastrectomy,” says Blaze.

Blaze lost her father to obesity-related disease when she was a teenager. He was 58. “As I was approaching 30, just thinking I’d already lived half my life, I wasn’t ready to face that,” says Blaze.

A vertical sleeve gastrectomy is a keyhole operation in which 75% of the patient’s stomach is removed.

“The volume of food that Amelia will be able to eat will be very small. There is also a very strong chemical effect from the operation where the hunger hormones are reduced. That’s the great secret weapon of the surgery,” explains Dr Ryan.

Bariatric surgeries are on the rise in Australia with around 23,000 done in the past year. Around 95% of these surgeries are done in private hospitals.

“We have this incredible inequality. It’s the most effective treatment but it's just not utilised by the lower socioeconomic half of our community that really can't afford to have it,” says Professor Dixon.

“It’s part of the discrimination and stigmatisation of obesity.”

The Obesity Myth:

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 A three-part documentary series that follows the struggle of morbidly obese patients and their families as they go through the weight loss program at Melbourne's Austin Health.