The best and worst diets 2016: three experts share their verdicts

Look out! Doctors caution against following celebrities like Pete Evan for health advice.
Look out! Doctors caution against following celebrities like Pete Evan for health advice.  Photo: James Brickwood

Still carrying the post-holiday food-baby? You're not alone. Diet Googling peaks in the first few months of the year when thousands of Australians turn to the internet in search of a diet that will shed kilos with minimal effort.

Separating science from fiction is tricky when it comes to diets (remember the "fat melting" grapefruit diet?). We asked three experts, Aloysa Hourigan, of Nutrition Australia, nutritionist Dr Joanna McMillan, and Clare Collins, Professor in Nutrition and Dietetics at the Newcastle School of Health Sciences, to voice their verdicts on the top 10 most Googled diets in Australia.

Detox: Not a diet that promotes good habits.
Detox: Not a diet that promotes good habits. Photo: Penny Stephens


What is it? Promotes a diet of foods closer to that of ancient ancestors. Banned foods include wheat, dairy, vegetable oil, grains, sugar, legumes, preservatives and processed food. Included is grass-fed meat, plant foods, herbs and spices, seafood, nuts, seeds, berries, nut milks and fermented drinks such as kefir and ghee or coconut oil.  

Aloysa Hourigan says: While it encourages an increased vegetable intake and avoids ultra-processed food high in salt, sugar and fat, and low in nutrients, the diet omits or severely restricts several food groups which provide key nutrients such as wholegrains, fruit, legumes and starchy vegetables. It encourages a lot of coconut oil and current research does not support the use of coconut oil as the preferred source of fat. It's also expensive, so not so good from a food sustainability perspective.

Professor Clare Collins says: The fatty acid content of meat today is not like that of wild animals in paleo times. High red meat intakes increase risk for bowel cancer. Not a diet to follow if you want to live a long life.

Dr Joanna McMillan says: Lots of marketing is cashing in on this diet – paleo brownies, paleo bread and cookies are all showing up and this is clearly ridiculous. Paleo humans did not have brownies even if they are made of raw cacao, avocado and coconut oil.

Calorie labelling is not working as well as we might think.

The 5:2 Diet. There's a danger on the that people may choose unhealthier foods on their '2' days. Photo: Getty Images



What is it? Dieters eat whatever they want for five days per week, then for two days drop their calorie intake to 2100 kilojoules for women and 2500 kilojoules for men.

McMillan says: There is some good evidence that fasting is good for us, so I don't mind this approach. It does teach people that they can go a day on little food and that being hungry is OK.  However, many people find it really hard to do in real life and usually the diet drops down to the "6 and 1", then the "7 and 0". There are also some concerns about loss of lean muscle.

Hourigan says: There is risk that on the five days people may choose more unhealthy foods and then the kilojoule and nutrient intake may not be well balanced and it may not work. It seems to suit some people but not everyone.

Collins says: This gets the "diet suffering" over quickly but you will probably feel hungry on the "fast" days, where the aim is to only have about 2000 kilojoules in total.


What is it? A diet restricting foods containing certain molecules that are poorly absorbed by some people and can cause them symptoms of IBS (irritable bowel syndrome). FODMAPs are found in foods high in fructose, (such honey and high fructose corn syrup); lactose (such as milk and soft, unripened cheese), fructans (such as wheat, onion and barley), galacto-oligosaccharides (found in beans such as baked beans, chickpeas and lentils), and polyols (such as avocado, mushrooms and some artificial sweeteners). 

McMillan says: This diet is being wrongly interpreted by many. It is not designed as a weight-loss diet but a treatment for IBS. In that regard it is very effective with good research behind it. However, it is not intended as a diet for life. Many healthy foods are omitted and the intention is to rebuild at least some of these back into the diet so tolerance develops and perhaps a change in gut bacteria which may be causing the problem in the first place.

Hourigan says: It is important that people do this with a dietitian and undertake the food challenges to ensure adequate nutrient intake and food variety.

Collins says: Only follow this if you are intolerant of FODMAPS and see an Accredited Practising Dietitian for help.

CSIRO diet

What is it? A high-protein, low-GI (glycaemic index) diet.

McMillan says: This is a good well-balanced diet approach. It suits many Aussies and has good research behind it. It's high in protein, low-GI and includes good fats. It won't suit vegans or vegetarians.

Hourigan says: Includes all the core food groups. There are good support materials (recipes, meal plans) and it encourages use of some healthy oils, lean meat and alternatives, as well as plenty of vegetables and moderate amounts of low-GI carbohydrate foods.

Collins says: Will work as long as you maintain an energy (kilojoule restriction). If you have a family history of bowel cancer, do not exceed the red meat intake recommended in the Australian Dietary Guidelines (up to 455 grams of red meat per week) and limit processed meat.


What is it? High-protein, low-carbohydrate diet broken into four parts or stages; attack (2-5 days), cruise (until you reach your ideal weight), consolidation (about 4 days per every ½ kilo lost), stabilisation (for life). This diet originated in France 30 years ago but became popular after Dr Pierre Dukan published a diet book in 2010.

McMillan says: Too many stages and unsubstantiated rules on this one for me. The basic premise of lower carbs and more protein is good, but it's way too complicated. 

Collins says: Some people like the structure but you will get bored quickly in the initial phases, eating lean protein, oat bran and low-starch vegetables. The omission of carbohydrate increases the risk of vitamin B deficiencies. Short-term symptoms of having no carbohydrates includes bad breath (it can smell like nail polish) and headaches. Also increases your risk of constipation and gall bladder disease. The initial weight loss on a low or no carbohydrate diet is partially due to emptying your stores of glycogen, which is stored with some water in your muscles and liver.

Hourigan says: Too many restrictions and rules – unlikely to be sustainable. Omits or severely restricts several food groups which provide key nutrients. Encourages excessive meat intake.

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Gluten-free foods

Some products promoted as 'gluten-free' also contain high amounts of sugar. Photo: Eddie Jim

Gluten-free diet

What is it? Avoids all food containing gluten.

McMillan says: This is not a weight-loss diet. If you are coeliac (less than 5 per cent of the population) you need a strict gluten-free diet. There may be up to 30 per cent of people with a gluten intolerance who would benefit from low gluten.

Hourigan says: Not all gluten-free foods are healthy. Many gluten-free commercially prepared foods can contain high amounts of sugar and saturated fat.

Collins says: See your GP to be tested for coeliac disease if you are concerned about this medical condition. This should only be followed by people with coeliac disease, which is an allergic reaction to gluten.

The Atkins

What is it? A low-carbohydrate, high-protein diet in four stages highly popular from the 1970s-1990s. The first stage is induction (about two weeks); followed by transition (when you're within six kilograms of goal weight); stage three increases carbohydrate intake (until goal weight is reached and maintained for a month); and stage four (lifetime maintenance).

Hourigan says: On the positive side, it discourages excessive intake of foods high in added sugar and high in refined carbohydrates. But it also omits or severely restricts several food groups which provide key nutrients, encourages high saturated fat intake, and does not address salt intake.

Collins says: Similar to the Dukan diet.

McMillan says: This has come a long way and now talks low-GI and at least the maintenance phase is more balanced. Low-carb diets are effective in the short term but can result in side effects such as lowered ability to exercise, bad breath and constipation. Fibre is very hard to get enough of on a very low-carb diet. However, there is some evidence you can adapt over a few months so I'm not against it for those who think this style of eating suits them.

The Mediterranean diet is rated well because of its emphasis on healthy fats such as fish, and vegetables.

The Mediterranean diet is rated well because of its emphasis on healthy fats such as fish, and vegetables. Photo: Jennifer Soo

The Mediterranean Diet

What is it? Promotes a diet of primarily plant-based foods, such as fruits and vegetables, wholegrains, legumes, nuts, olive oil and fish, while reducing intake of red meat.

McMillan says: It's believed true paleo was closest to a Med way of eating than anything else and not as low-carb as paleo seems to be interpreted. Good evidence behind the Med Diet shows heart and anti-cancer benefits and weight control. Tasty, good fats, moderate carbs (but what I call smart carbs (low GI)) and loads of plant food.

Collins says: You won't lose weight unless you drop your total kilojoules intake but you will have a healthy eating pattern.

Hourigan says: Achievable; evidence-based; includes all core food groups.

Ketogenic diet

What is it? A high-fat, low-carb diet that creates a metabolic process called ketosis that occurs when the body does not have enough glucose for energy and begins to break down stored fats for energy. About 70 percent of the kilojoule intake in this diet comes from fat, 20-25 per cent from protein and 5-10 per cent from carbohydrates.

McMillan says: Showing promise in treating epilepsy and there are some good studies in treating obesity, but this is not a pleasant or easy diet to follow, so I don't see it being a widespread solution.

Collins says: Another variation of the low-carbohydrate diet. It is a high-fat, adequate protein, low-carbohydrate diet. Historically this test diet has been used to try to treat unresponsive epilepsy in children. This diet needs medical supervision.

Hourigan says: It encourages high saturated fat intake and does not address salt intake. It may have a negative impact on health for some people, for example, people suffering gout or with heart disease. It's expensive; so not so good from a food sustainability perspective.

The detox diet

What is it? Fasting or low food intake diet designed to "cleanse the liver", often supported by packaged powdered drinks or bottled tonics.

Hourigan says: Any weight lost during the detox phase is likely to be regained when you return to a more regular food intake. Sometimes it can be a motivator for people to change their mindset when aiming to improve their health and wellbeing, but it is potentially dangerous if continued past the recommended time frames.

Collins says: The risks are the same as for low-carbohydrate diet. This diet also increases your risk of constipation, gall bladder disease and nutrient deficiencies. The best way to "detox" your body is to avoid consuming the things that put more pressure on the liver and kidneys, such as alcohol, drugs and excessive protein intake.

McMillan says: I hate the word detox – scientifically it's nonsense. Your liver has the job of detoxing all the time and there is no evidence that any diet (bar cutting out things like alcohol) does any more detoxing. I think it just plays on our guilt. It's much better to change habits for life rather than doing a few days of a so-called "cleanse".

So what's the best?

Hourigan and McMillan both selected the Mediterranean as the best option, while Collins believes the best approach is one that gives you a nutritionally adequate intake and that satisfies you and most importantly you can stick with long-term.

And the worst?

Our experts are in agreement on this one, nominating the detox diet.