Back in 1961, Jean Nidetch was mistaken for pregnant during a trip to the supermarket. Mortified, she immediately began a strict diet, reached her "goal" after a year and managed to keep it off until she died at the age of 91 in 2015.

Oh, and she also founded the multimillion-dollar weight loss empire that is Weight Watchers.

But stop right there. If you're thinking that Mrs Nidetch is a weight loss inspiration, the truth is, about 95 per cent of people who lose weight on a diet will regain it all within one to five years and about a third of those will end up heavier than before they started, reports news.com.au.

From a dieting point of view, Mrs Nidetch is a freak who made dieting her livelihood and insisted her coleslaw be washed of its dressing every single time she ordered it.

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"If you look at the science behind weight loss and dieting, it becomes obvious that nothing works," says Australian psychologist Louise Adams.

"Everyone can lose weight, but after about six months the weight loss reverses. The evidence that weight loss dieting leads to weight regain is just as strong as the evidence that shows smoking causes lung cancer."

Adams started her private practice in the mid-2000s and while she didn't specialise in body image or diet, almost everyone who came to see her had some kind of worry about their body.

"I'd had quite a lot of training in eating disorder treatment when I was at uni," Ms Adams said, "but I didn't know a lot about how to help people lose weight in a healthy way.

"I'm an evidence-based practitioner, so I did research and the more I learnt about dieting and weight loss, the more I realised that I couldn't ethically help someone diet because I'd ultimately be setting them up for failure."

So if dieting is a waste of time, does that mean we may as well eat Ben & Jerry's for breakfast and hot chips for lunch?

Not exactly.

Like an increasing number of health professionals worldwide, Ms Adams is an advocate for the Health at Every Size movement.

The approach is based on Dr Linda Bacon's book, Health at Every Size, that argues for a compassionate, weight-neutral way of addressing health and wellbeing.

"Restrictive dieting causes so much damage, not just in terms of weight regain, but the psychological damage ranging from obsessions with food, disordered eating, low self-esteem and shame is significant," Ms Adams said.

"Dieting disconnects people from their bodies, it teaches you to ignore hunger cues and ignore what your body needs. Health at Every Size helps people connect with their bodies, to respect them and care for them."

Rather than calorie counting, weigh-ins and 'good' and 'bad' foods, the non-diet approach focuses on health behaviours and intuitive eating which includes listening to what your body needs and trusting what it tells you.

"It's about an attitude," Ms Adams said. "You should desire to take care of yourself because you value the way you are right now. We don't take care of bodies that we hate. Have pride in your body. Appreciate what it does for you every day."

In a diet-saturated culture that bombards us with the myth that losing weight is a gold ticket to happiness, it can take time for people to abandon dieting completely.

"It's scary but it's also unbelievably liberating," said Ms Adam. "Instead of obsessing over food and weight, food just becomes food.

"A lot of people will binge at first when I tell them to stop restricting and that's normal. But that phase usually passes quite quickly."

In diet culture so many of us are model prisoners, obediently listening to weight loss messages and constantly trying to lose weight, Ms Adams said. And she wants that to change.

"I want Weight Watchers to go broke," she declared. "I want us to appreciate a diverse range of body sizes and for our New Year's resolution to be: 'I will never diet again,' rather than: 'I need to lose five kilos'.

"I tell people to write down all the diets they've been on. Often there have been quite a few and I ask people how they felt when they were at their thinnest," Ms Adams continued.

"At first they say they felt confident, that they got a lot of compliments, that they enjoyed being thinner. But then when we go deeper and we talk about real happiness, it becomes clear that happiness is not weight related."

Having seen the positive impact of the non-diet approach to healthcare in her own practice, Ms Adams has now established Untrapped, an online program that teaches intuitive eating, body positivity and critical thinking against the diet industry.

Or, as she puts it, freedom from "diet prison".

"I'm lucky because I am surrounded by professionals who agree that diets are bulls**t," Ms Adams said. "We are so inundated with messages that promote dieting, it's important to surround yourself with others who are critical of the diet industry, which is what Untrapped does.

"Get angry. Tell that voice in your head that says you need to lose weight to bugger off. Let's topple diet culture for good."

Michelle Celander, Dietitian and Ph.D., Director of Program and Content, Weight Watchers Australasia later told news.com.au: "We agree that dieting leads to deprivation and that a livable approach is a sustainable one. And we believe that health goes way beyond calorie-counting and a number on the scale.

"Weight Watchers helps people establish healthy habits that are rooted in science and is the most clinically studied weight management program in the world.

"We help people to develop an eating pattern that is aligned with The Australian Dietary Guidelines, find what moves them to become more active, and shift their mindset about weight, health and happiness."