Our obsession with clean eating has resulted in some radical diets, from five-day juice cleanses to pH diets featuring delicious alkaline ash.

Celebrity chef Pete Evans' documentary The Magic Pill — which depicts a high fat, low carb diet as a treatment for autism, asthma and cancer — has sparked controversy, but it's hardly unique.

Wellness gurus claiming to have the cure for all manner of modern ailments are now a feature of contemporary culture.

What we eat is increasingly determined by a moralism that distinguishes between good and bad, clean and dirty, pure and impure.

So why, in a society where science is king, are we so eager to believe in the magical healing power of green juice?

Deakin University's Dr Christopher Mayes suggests there is a backlash against the dominance of the technological approach to food — and its perceived failure.

Sorry, this audio has expired What's behind our preoccupation with clean eating?

"There's a sense that there's been science-based nutrition advice for decades coming out of various government health agencies and various science bodies, but also this feeling that there is a greater propensity of chronic and diet related diseases," he says.

"So this magic thinking is a reaction to that — that this overly rationalistic ... technologically-based view of food is not delivering on the health promises but is, perhaps, undermining it."

While it's easy to dismiss some of the more outrageous health claims as modern-day charlatanism, there is clearly something in appeals to cleanliness, purity and detoxification that resonates with people.

If our food isn't toxic, is there something about modern life that we feel is contaminating?

Dr Mayes says food is a powerful metaphor for broader social and cultural anxieties.

"This is the idea that our society, and ourselves, have become alienated from some natural or ideal order," he says.

According to Dr Rachel Ankeny, a professor in humanities at the University of Adelaide, nostalgia is often a reaction to a growing anxiety around food.

"In a lot of the research we do on values associated with food and agriculture, people are very keen to return to how things were, traditional ways of producing food," she says.

"It's not necessarily accurate history, but I think it reflects a desire people have to do better."

And do better we must. We're told it's our affluence and abundance that has made us sick — along with and corrupt multi-national food companies selling us sugar and salt.

From diabetes to obesity, Alzheimer's to almost every form of cancer, our diets, the story goes, are toxic.

The mystification of 'clean', natural, unprocessed food becomes very appealing.

"Even in the so-called 'legitimate' discussions around food … clean is seen as representing healthy, and unclean as unhealthy," Dr Mayes says.

"A lot of what's considered impure or dirty or unclean are the processed foods.

"The foods that are bought through supermarkets tend to be also the foods that are affordable, common and eaten cheaply — which a majority of people, particularly those on middle and low incomes, have ready access to."

Wellness as personal responsibility

The message underpinning a lot of modern diets is that the foods we do and don't eat are matters of individual choice.

Talking about good and bad food becomes a way of talking about good and bad people.

If health and wellness are choices, then by extension poor health is a personal failure.

The message underpinning a lot of diets is that if you'd prefer this to a green smoothie, you're a bad person. ( Unsplash.com: Robin Stickel, CC-0 )

"The moralising currently associated with food and choice is highly dangerous," Professor Ankeny says.

"[It] reinforces a neoliberal notion that all decisions are wholly individual ones, when in fact the food system is part of a broader social, economic and cultural context.

"In Australia we have certain geographical locales and cultural groups which struggle with access to appropriate foods.

"We need higher-level efforts (for example, via policy) to improve these conditions for all."

The punishing logic that contrasts people practicing a healthy lifestyle with 'irresponsible' citizens making the wrong choices is not just the preserve of wellness warriors and diet gurus, Dr Mayes says.

"A lot of government health campaigns and public health programs also emphasise individual choice and responsibility in relation to diet, which implicitly blames individuals for their ill-health without addressing more fundamental factors," he says.

At the same time, we are told to exercise self-care, to 'forgive' ourselves and to indulge in guilty pleasures while also depriving ourselves of sugar, fat, gluten and carbs — and ensuring our slender bodies glow, inside and out.

A new ethics of food

While this all may seem disorienting, the relationship between food and morality can be traced back a long way, Professor Ankeny says.

Food prohibitions, as well as a preoccupation with purity, have long been central to most organised religions.

"In modern — at least Australian — society, religion isn't as much of a driver for many people but being a vegetarian or being a locavore or whatever else has come to be part of many people's identity claims," she says.

"It may well be, in the absence of organised religion, [that] it gives us a way to think about ourselves, to think about who's with us and who's against us."

Dr Mayes says many people are thinking more critically about what they eat and are considering the political and ethical impacts of their food, rather than just worrying about health concerns.

It seems unlikely that food might one day be a source of unqualified pleasure. So too, that raw cauliflower "rice" will make you glow and avoiding vegetables in the "nightshade family" will cure your IBS.

While cleanliness and purity may not be helpful categories, the desire to do better and think more deeply about the ethics and politics of the food we eat may in fact prove to be our ultimate "cure".