Australasian Science: Australia's authority on science since 1938

Diet Gurus Ignore the Weight of Evidence in Guidelines

By Rosemary Stanton

Diet gurus are blaming Australia’s obesity problem on government dietary guidelines they claim are unhealthy, when the real issue is that too few people follow them.

It’s hard working in public health nutrition in Australia. Not only do we try to cope with Australia’s massive weight problem – 70% of men, 56% of women and 26% of children and adolescents are overweight or obese – but nutritionists are now being blamed for the disaster.

Netflix has recently been criticised for streaming a program produced by celebrity chef Pete Evans that claims the medical profession has an interest in keeping Australians unhealthy. The recommendation of the program’s self-described “experts” include claims that a low-carb/high-fat diet can even cure autism, asthma and some cancers. The evidence produced consists of single case studies with no understanding that anecdotes do not equal evidence.

According to these and other self-styled diet gurus, Australia’s obesity problem has arisen because our dietary guidelines “got it wrong”. This message is now being spread among their massive numbers of social media followers.

It’s possible these critics have not actually read the guidelines (see https://www.eatforhealth.gov.au). It’s also possible they don’t understand the National Health and Medical Research Council’s strict criteria for the evidence statements that are included in the guidelines. However, the main silliness lies in blaming the guidelines for Australia’s obesity when so few people follow them.

The Australian Bureau of Statistics notes that fewer than 4% of Australians eat enough vegetables, fruit consumption is just half the recommended two pieces per day, and two-thirds of grains eaten are refined rather than the wholegrains recommended.

The elephant in the room is the fact that 35% of adults’ and 40% of children’s energy intake comes from energy-dense, nutrient-poor discretionary foods and drinks. These “junk foods” also account for 58% of the average family’s food budget. The widespread promotion and marketing of these foods has been remarkably successful.

A point ignored by the guideline critics is that these junk foods are not recommended. Indeed, the guidelines note that many Australians have no room in their daily diet for any of these foods.

Our dietary guidelines are based on foods, but the self-styled diet gurus prefer to describe nutrients. Their favoured diet is minimal carbohydrates, modest protein and lots of fat. This diet bans all grains and legumes and dairy products (except butter), and restricts most fruits and even some vegetables because of their carbohydrate content. Most of the alternative diet gurus have a particular beef with the dietary guidelines’ advice to limit foods that are high in saturated fat.

Sugar is out, too – a point many accuse the dietary guidelines of missing. In fact, since their first issue in 1981, Australia’s dietary guidelines have advised the public to avoid eating too much added sugar. They now include lists of sugary foods to limit. These include soft drinks and cordials, energy drinks, sports drinks, fruit drinks, vitamin waters, confectionery (including muesli bars and chocolate), cakes, sweet muffins, biscuits, pies and many desserts.

A high fat/low carb diet is very likely to achieve short-term weight loss. There’s no mystery to this – so many foods are forbidden by this diet that the total kilojoule intake inevitably falls. However, evidence shows that losing weight is not the hard bit – keeping the weight off is. And any long-term diet for weight loss needs to be healthy and sustainable.

Fortunately, the evidence base has been enhanced with a recent study that assigned more than 600 people to one of two dietary patterns: low in either fat or carbohydrate (https://goo.gl/JptKaM). Over the following months, each group was told to increase healthy food sources of either fat or carbohydrate to levels they felt they could happily follow forever.

The group that had started on a very low-fat diet increased their intake of healthy sources of fat, and ended up with a level that actually fitted with what dietary guidelines recommend. Those who started on the low-carbohydrate diet also increased their intake of healthy sources of carbohydrate, again avoiding the high levels of sugar and refined starches that characterise the usual diet in countries such as Australia. Again, their diet fitted well with what is recommended in the dietary guidelines.

After 12 months, the results for each group were equally good, and this applied whatever the participants’ genotype pattern or baseline insulin levels. The new study was truly a win for an evidence-based solution. Sadly, it’s been ignored by those who prefer extreme diets.


Dr Rosemary Stanton OAM has worked in public health nutrition for more than 50 years. She is currently a Visiting Fellow in the School of Medical Sciences at the University of NSW and has authored many scientific papers, written more than 30 books (including textbooks) and thousands of articles for the popular press.