The average health-conscious Australian could be forgiven for being a little confused about what constitutes an optimal diet.

Nutritional information – whether scientifically proven or otherwise – saturates our culture. Whether it’s from celebrity chefs on our TV screens or books on super foods on our shelves, the overload of nutritional information available has made the seemingly simple task of healthy eating somewhat overwhelming.  

Think back, just a few years ago, nuts weren’t ‘activated’ and most people hadn’t heard of quinoa or kale.

Today, popular diets like gluten-free and Paleo are big business. Changing food trends are even affecting the way chefs in some of our top restaurants write their menus, and diet-specific cafes have opened in our suburbs.

But with the rise in these so-called healthy eating trends, Australia is still ranked as one of the fattest nations in the developed world. With obesity increasing the risk of many chronic diseases, the impact of what we put in our mouths is immense.

It’s no wonder many people are more confused than ever about what to eat.

We’ve asked UniSA’s experts in nutrition to consider the big diet confusion and put us on the path to a healthy lifestyle.




Professor Peter CliftonUniSA’s Professor of Nutrition Peter Clifton says obesity is due to the consumption of more calories than is needed by the body for energy.

Co-author of the well-known CSIRO Total Well-Being Diet, Prof Clifton says all types of calories in excess cause obesity, whether they are fat (saturated or unsaturated), carbohydrate (sugar or starch) or protein (meat, dairy or vegetable).

He says reducing calories from any source will slow weight gain and, if the reduction is large enough, cause weight loss.

“Which is the easiest food type to reduce depends on personal preference,” he says.

“For some people sugar or carbohydrate reduction is easier than fat reduction; for others the reverse. It also depends on what food group contributes the most to the energy excess as this may be easier to reduce. So if you have a sweet tooth and eat a lot of sugary foods, it’s sensible to reduce these as much as can be tolerated without feeling too desperate.

“That said, there are several good reasons not to reduce protein much, if at all. Protein is an essential nutrient, and eating it tends to make people feel fuller than carbohydrate or fat. Protein also requires a little more energy to metabolise so it helps with weight loss and weight maintenance, and may also reduce the inevitable loss of muscle and bone that occurs with weight loss.”




The Paleo diet is currently one of the world’s most popular diets, but Prof Clifton says the evidence is not strong enough for everyone to start eating like our caveman ancestors.

“Paleo diet advocates say our bodies have not evolved to deal with modern foods like carbohydrate, with or without fibre, or foods that combine carbohydrate and fat, but there is no real evidence for this,” Prof Clifton says.

“Avoiding modern foods like carbohydrate will reduce calorie intake and we will lose weight.

“Reducing low fibre carbohydrate foods will certainly reduce our glycemic load and reduce our risk of type two diabetes and heart disease, but eating more fibre-rich whole grain foods – which is a definite Paleo ‘no-no’ – will reduce these diseases as well.

“Our gut bugs love that fibre and produce lots of short chain fatty acids which appear to be very helpful for us.”

On gluten-free diets, Prof Clifton says quite simply, eating gluten-free is essential for those with celiac disease but optional for anybody else.

“Some people do feel better eliminating wheat from their diet and have fewer symptoms such as bloating, but consuming a gluten-free diet is not associated with less chronic disease,” he says.

When it comes to detox diets, Prof Clifton says detox is a rather meaningless phrase.

“Certainly going off alcohol for a while is a good strategy especially if you over consume, but fruit juice-only diets or coffee enemas certainly have no data to support them,” he says.




Dr Tom WycherleyThe sugar-free food movement has garnered a significant following with top selling books such as Sweet Poison and I Quit Sugar taking off in recent years.

Avoiding food and drinks with added sugar – rather than unprocessed foods like fruit which contain natural sugar naturally – can be a sensible strategy to achieve a healthier diet, according to Dr Tom Wycherley from the School of Population Health.

“Whole foods that contain sugar should not necessarily be avoided since they can still contribute many key nutrients to our diet. Fruits contain the sugars fructose, glucose and sucrose but are also rich in vitamins and fibre, and milk contains the sugar lactose but is a great source of calcium and protein,” he says.

“However, refined sugar – typically in Australia purified sucrose from sugarcane that is added during processing to primarily enhance taste – contributes calories without any nutritional benefits. This is perhaps most apparent with sugar-sweetened drinks.”

Dr Wycherley says overconsumption of added sugar may cause weight gain and could also contribute independently to the risk of developing type two diabetes and cardiovascular disease, by increasing blood glucose and insulin concentrations and subsequently promoting inflammation, insulin resistance and impaired beta-cell function.

“Avoiding foods and in particular drinks with added sugar may represent a sensible strategy to avoid surplus calorie intake and adverse cardio-metabolic effects without compromising the nutritional quality of the diet,” he says.




Professor Jennifer KeoghUniSA Associate Professor of Dietetics and Nutrition Jennifer Keogh says most of the salt we eat comes from salt added in the food manufacturing process.

“In one of our studies 20 per cent of salt intake came from breads and cereals and six per cent came from sweet and savoury biscuits, cakes and desserts. Processed meats such as ham contributed 15 per cent and fast food and takeaways was seven per cent,” she says.

“Only 1.5 per cent of the salt we eat comes from adding salt to food in cooking and just before we eat it.”

Assoc Prof Keogh says that while some salts claim to be healthier than others, all salt contains the same amount of sodium and chloride.

“Sea salt is often promoted as being healthier but sea salt and table salt have the same nutritional composition. Evaporation of sea water leaves behind some trace minerals and elements which add flavour and colour to sea salt,” she says.

A Fellow of the South Australian Cardiovascular Research Development Program, Assoc Prof Keogh says high salt intake is associated with high blood pressure and can cause damage to the lining of the blood vessels.

“The good news is that increasing potassium by increasing your intake of vegetables and fruit may dampen the damaging effects of a high salt intake,” she says.




Dr Sze Yen TanContrary to the popular thought that ‘nuts make you fat’, eating nuts may actually help to regulate body weight, according to dietetics lecturer Dr Sze Yen Tan.

Dr Tan says nuts have several health benefits, such as reducing blood cholesterol, improving vascular function, and helping in blood sugar regulation.

“Nuts are high in energy (and therefore calories) which make them less appealing to people who are watching their body weight or trying to lose weight,” Dr Tan says.

“However, these concerns are not warranted. Epidemiological studies have shown that eating nuts more frequently or in bigger quantities is associated with lower body weight. This association is further supported by evidence from clinical studies.

“In most clinical trials, not only did supplementing nuts to a habitual diet show no links to weight gain, but in some cases nuts even promoted weight loss.” 

Dr Tan says the effects of nuts on body weight maintenance could be explained by a number of factors, including nuts’ ability to suppress appetite, an effect that was more pronounced when nuts were ingested alone as snacks, as well as lower-than-expected energy from nuts available to the human body. One study reported that only about
68 per cent of energy from almonds was absorbed.

Nuts can therefore be considered part of a healthy diet.




Dr Natalie ParlettaSenior Research Fellow in Population Health and Nutrition, Dr Natalie Parletta, says research has confirmed the many benefits of a traditional Mediterranean-style diet.

“The Mediterranean diet has received much attention over the years, and its many health benefits include reduced risk of diabetes and heart disease, and superior weight loss benefits compared with a low fat diet,” she says.

“It is primarily a whole food diet that is rich in plant foods such as vegetables, fruit, legumes, nuts, seeds, whole grains and generous use of extra virgin olive oil, fish and moderate consumption of red wine – mostly with meals.

“It includes very low intakes of red meat, processed foods and refined carbohydrates. One of the great things about this diet is that the food is delicious and provides an abundant variety of options – and can therefore become part of a healthy lifestyle.

“This is a key factor in maintaining any diet. The majority of people who go on a restrictive diet to lose weight – even if they are successful – will invariably put the weight back on. This is because in the long-term the diet is simply not maintainable.   

“Successful weight loss and maintenance comes from enjoying and celebrating good healthy food as part of a healthy lifestyle.”

Connect with Dr Parletta: @NatalieParletta

Find out more at the UniSA Sansom Institute for Health Research website.