Fad diets: what do dietitians say about the latest crop?

June 2015 Vol 15 (3)

Any diet that bans fruit has to raise eyebrows. The same goes for a diet that advocates lashings of cream and butter with every meal. The demonising of one food group as the source of all dietary evil, or the fixation on another as a saviour, is often the key selling point for the latest fashionable weight loss diet.

With increasing numbers of New Zealanders being overweight or obese – and increasing numbers of people being diagnosed with type 2 diabetes and heart disease – the ‘appetite’ for trying new dietary regimes is also growing.

While nurses and dietitians may advise clients to make gradual changes towards more sustainable and healthier eating patterns, many people with long-term conditions want to speed up the changes and are drawn to the latest reduction/detox diet making headlines.

So how should nurses advise their type 2 diabetes and heart patients on the pros and cons of some of the latest fashionable diets?

Nursing Review talks to Diabetes New Zealand dietitian Margaret Thorsen and Heart Foundation nutrition spokesperson Dave Monro about four of the current dietary trends: the Paleo diet, the 5:2 intermittent fasting diet, the ‘no sugar’ regime and the low-carb, high-fat (LCHF) approach.

The dietitians give thumbs-up to some of the positive take-home messages common to the latest fashions, highlight some of the pitfalls or dangers, and also share some advice on guiding long-term condition and other patients towards sustainable healthy eating habits.


The healthy eating approach

Diabetes New Zealand advocates that the best weight management strategy for most people is a moderate, balanced diet coupled with regular physical activity.

Margaret Thorsen, a Diabetes New Zealand dietitian, acknowledges the moderate approach is sometimes a ‘hard sell’. But repeatedly eating too many calories, regardless of their source, can lead to weight gain and put people on the path to type 2 diabetes. Healthy eating patterns lead to more stable blood sugars, so those with pre-diabetes are less likely to progress to full diabetes and when diabetes already exists, it can be better managed.

If a new dietary regime helps somebody to kick start a new healthier eating pattern, that is a positive, adds Thorsen. It just needs to be sustainable change. If people repeatedly start and stop reduction diets – as they struggle to comply with a dietary regime’s rules – they risk yo-yoing weight loss and gain which can have a detrimental effect on their metabolism.


Diet needs to be realistic

Heart Foundation dietitian Dave Monro and Thorsen agree that for healthy eating changes to be sustainable they also need to be realistic. If a diet takes a ‘thou shalt never have’ approach to a particular food, or food group, then those items can become much more desirable. Then if that forbidden food is eaten the person can feel they have ‘failed’ the diet and may return to old eating habits.

Thorsen says one positive aspect across many of the new eating fashions is their emphasis on moving away from processed, pre-packaged foods to cooking from scratch using fresh whole foods so people know what they are eating. But they both say the reality is that not everybody’s supermarket budget stretches to cover the high-quality ingredients often promoted in such diets. Today’s busy families are also often time poor so struggle to regularly cook from scratch and often fall back on processed foods to get dinner on the table quickly.


Fat is a fad topic

Fat intake has been one of the hot media topics of recent years, with many arguing that the pendulum has swung too far in damning dietary fat. But Thorsen and Monro agree that doesn’t mean the pendulum has swung back so far that a high saturated fat intake is now okay – science still shows saturated fats have a negative impact on heart health.

Monro says the healthy heart message focuses less on a low fat diet and more on reducing one’s saturated fat intake. “So it is fine to have a slightly higher fat diet but keep the saturated fat content in the diet low.”

He says there has been a range of factors causing heart disease rates to plummet over the past 50 years and key amongst them has been reducing saturated fat intake.

Thorsen agrees, saying that some heart-friendly fats are okay. “Olive oil, avocado and nuts, including some peanut butter on your toast, can be part of a healthy diet,” she says. (See also some general healthy eating tips at end of article.)


Click here to download the 4 page fad diets PDF

Also click here to read opinion pieces prompted by this article and published in the following edition of Nursing Review (Vol 15 no. 4)


Lettuce Fork ICONThe 5:2 diet (intermittent fasting)

This diet involves eating normally five days a week (2,000 calories or 8,400 kilojoules a day for women) and then cutting one’s calorie intake down to a quarter of that for two days of the week (for example Monday and Thursday). This means eating 500 calories (2,100 kilojoules) a day for women and 600 calories (2,500 kilojoules) for men.

The argument for intermittent fasting is that occasionally eating less is an easier dietary regime to comply with than cutting calories every day. If people eat sensibly, it advocates (that is, don’t binge or overeat on the other five days), they will lose weight. Research is also ongoing into whether intermittent fasting may have other health benefits.

Allowed: all foods in a normal balanced diet with a calorie intake of around 2,000 calories a day for woman and 2,400 for men.

Not allowed: more than 500 or 600 calories during the two fasting days.

This diet regime clearly states that intermittent fasting is not suitable for children (under 18 years), people with type 1 diabetes or people with type 2 diabetes on medication (other than Metformin), pregnant woman and people recovering from surgery.


  • Maintaining a healthy diet on the non-fasting days is encouraged, so this diet may help to break unhealthy dietary habits
  • Unlike other, more rigid, dietary regimes, no specific food groups are banned
  • As participants can eat a normal, healthy diet most of the time, it may be easier to comply with.


  • Unsuitable for people with type 1 diabetes or people with type 2 diabetes on medication (other than Metformin) because of the risk of hypoglycaemia on fasting days
  • Not everyone will be nutritionally competent enough to cut their dietary intake down to 500 calories on fasting days
  • The energy levels of some people – particularly those who have physically demanding jobs, or are active – could be compromised and they could feel extremely tired on fasting days
  • People with diabetes would need to monitor their blood sugar levels on fasting days
  • Yo-yo eating habits that may not be healthy or sustainable could be encouraged.


The Centre for Endocrine, Diabetes and Obesity Research (CEDOR) at Wellington Hospital is currently researching the effect of intermittent fasting (the 5:2 diet) on blood sugar levels and diabetes management, including changes in medication requirements, hormone levels and weight, and how well the diet is tolerated.

The argument for intermittent fasting is that occasionally eating less is an easier dietary regime to comply with than cutting calories every day.


Burger ICONLow-carb, high-fat (LCHF) diet

In an LCHF diet participants slash their carbohydrate intake and eat a diet high in saturated fats. At the most extreme end is the ketogenic diet (developed to prevent epileptic fits), which has a strict 4:1 ratio of fats to proteins and carbohydrates and leads to falling blood sugars and the rise of ketones as the body switches from breaking down glucose for energy to breaking down fat. This can cause ketosis, which can result in nausea, headaches, fatigue and bad breath.

Allowed: meat, fish, eggs, cured meats like salami and bacon, vegetables growing above ground (i.e. not potato or kumara) and natural fats (including butter, cream, full-fat cheeses, full-fat plain yoghurt and other full-fat dairy products, the fat on red meat and the skin on chicken). Berries in moderation.

Not allowed: sugar and starchy foods (like bread, pasta, rice, beans and potatoes, including chips), low-fat products, sweetened dairy products like fruit yoghurt or ice cream, vegetable oils, trans fats and margarine. In many versions of this regime you are encouraged to reduce or cut out your fruit intake.


  • Foods with a high protein or fat content can increase feelings of satiation or fullness
  • Refined carbohydrates (like those in sugary drinks, white bread and cakes) are not necessary for a healthy diet.


  • Not suitable for people with type 1 diabetes or people with type 2 diabetes on medication (other than Metformin) because of the risk of hypoglycaemia or ketoacidosis
  • Some people only hear part of the message and see it as a licence to eat high levels of saturated fats, such as butter and fatty meats, without changing other aspects of their diet
  • A high saturated fat intake results in a higher cardiovascular risk; the reduction in saturated fat intake in the past 50 years has been an important factor in reducing heart disease rates
  • A blanket restriction on all carbohydrates is too restrictive and unnecessary
  • Some highly nutritious foods that contain carbohydrates – like whole grains, legumes and vegetables – have been shown to protect against heart disease
  • The restrictive nature of this diet means it may be unsustainable in the long term
  • Some versions suggest taking a multivitamin supplement, suggesting the restricted diet was not providing all the necessary vitamins and minerals.

Some people only hear part of the message and see it as a licence to eat high levels of saturated fats.


The Paleo dietPaleo Diet ICON

The Paleo approach is to eat modern foods while trying to mimic the food groups eaten by our hunter-gatherer ancestors before they began growing crops and farming animals. Interpretations of this diet can vary, with some people adopting the ‘85:15 rule’ whereby they are allowed to consume three non-Paleo meals per week, including a glass of wine.

Whether Palaeolithic times were a golden era for human nutrition is open to debate, though if our ancestors did manage to have meat at the fireside every night, they probably had to expend more energy to catch it than just driving to the supermarket.

Allowed: grass-produced meats, fish, seafood, fresh fruit and vegetables (excluding starchy vegetables like potato), eggs, nuts and seeds and ‘healthy’ oils including olive, avocado and coconut.

Not allowed: cereal grains (so no wholegrain bread, porridge or rice), dairy products, legumes (i.e. beans, lentils, chickpeas and including peanuts), refined sugar, potatoes, processed foods, salt and refined vegetable oils.


  • Encourages people to move away from processed foods and refined starches
  • Promotes cooking of whole foods from scratch
  • Could help to retrain the palate away from sweetness and salt


  • Not suitable for people with type 1 or type 2 diabetes because of the risk of hypoglycaemia through low carbohydrate intake
  • Excludes foods that modern science has shown help to protect against heart disease 
  • i.e. legumes and unrefined whole grains
  • Eliminates other food, such as low-fat dairy and starchy vegetables, which also contain valuable nutrients
  • When early man had to hunt for meat it featured less often in their diet – the Paleo diet should not be seen as a licence to overdose on meat or animal fat
  • Can be costly in time and money to shift away from all processed foods, to purchase some of the foods promoted in this diet and to cook food from scratch.

 … if our ancestors did manage to have meat at the fireside every night, they probably had to expend more energy to catch it than just driving to the supermarket.



No Sugar ICON‘No sugar’ diet 

Some recent diets concentrate on severely reducing or eliminating added sugar to ‘detox’ and lose weight. Advocates point out that the advent of low-fat foods saw food manufacturers use more sugar and sweeteners (like corn syrup) to compensate for the reduction in flavour and make their products more palatable.

Increased sugar consumption is now regarded by many as one of the major causes of the world’s rising obesity levels. A can of fizzy drink, for example, can contain 9–10 teaspoons of sugar.

The response has ranged from people aiming to reduce sugar intakes to WHO recommended levels (around 12 teaspoons a day from all added sugar sources or ideally half that level) to people trying to eliminate all sugars from their diet, including not only fruit juice but also fruit itself.

Allowed: vegetables, fruit, nuts, meat, eggs, natural yoghurt, cream and cheese (milk sugar i.e. lactose is okay), bread with no added sugar.

The emphasis is on natural, unprocessed foods. Some ‘no sugar’ plans still allow dry wine, beers and spirits but not liqueurs, dessert wines or mixers like tonic.

Not allowed: sweetened milks, fruit juices, honey, cured meat products, maple or corn syrup, table sugar (beet or cane), confectionery, muesli bars, any baked goods or breakfast cereals with added sugar. People are encouraged to read food labels carefully for ‘hidden sugars’. Some also advocate not eating fruit.


  • Encourages people to move away from processed and sweetened foods Promotes cooking of whole foods from scratch to reduce chance of getting hidden sugars in processed food
  • Avoiding unnecessary added sugar in the diet is already recommended for people with diabetes and those with pre-diabetes
  • Taste buds could be retrained to prefer less sweetness in food.


  • Not suitable for someone managing their diabetes with insulin or any medication that could lead to hypoglycaemia as they need a source of immediate, fast-acting sugars (like glucose tablets) in case of a potential ‘hypo’ incident
  • Trying to avoid all added sugars may be unsustainable; probably better to first focus on reducing sugar intake in drinks or other commonly consumed foods and allow taste buds to adjust
  • Can be costly in time and money to shift away from processed foods and to cook and bake food from scratch
  • Reducing one’s added sugar intake is positive but becoming obsessed about a single nutrient can be problematic
  • Some people take it to extremes and don’t just avoid added sugar but stop eating fruit (contains natural fructose) and drinking milk (because it contains lactose), when both foods have positive nutritional benefits
  • People may become preoccupied with removing sugar from their diet and ‘loosen the reins’ in other dietary areas.


Diabetes New Zealand says a small amount of sugar in the diet is allowed for people with diabetes but should be consumed in appropriate amounts AND times to avoid spikes in blood sugar levels.


Healthier eating ICON

Healthier eating tips for you and your patients 

Check your drinks:

Aim to drink predominantly water, milk and sugar-free coffee or tea and steer away from sugary drinks.

Look at your meal pattern:

Are you having three regular meals spread throughout the day? If you are eating a snack between meals, is it a healthy snack? Are you ‘grazing’ in the evening and eating more than you think?

Serving sizes:

is your plate following the Diabetes New Zealand healthy plate model of ½ vegetables, ¼ protein and ¼ carbohydrates?

Fine tuning:

Once you’ve addressed the above three areas then you can start fine-tuning the meals you eat to better manage your weight or blood sugar levels.

Be realistic:

Dietary changes have to be sustainable and fit in with people’s budgets, lifestyles and available time. For example, it may be difficult to eliminate all processed foods but try and make good choices whenever possible.

Coconut oil is not healthier than unsaturated oils: 

check out the Heart Foundation’s findings on this other fad at

Don’t get fixated on nutrients:

people don’t eat nutrients, they eat food, and people should focus on trying their best to eat healthy food.

As writer and researcher Michael Pollan sums it up:

if a patient wants specialist help to change and improve their diet, refer or suggest a dietitian.

Get the basics right:

Eat MORE vegetables and whole foods and eat LESS processed food, refined starches and added sugars.

Don’t get fixated on whether foods contain carbohydrates:

it is the type of food that matters more than the carbohydrates it contains i.e. whole grains get a tick and refined white flour gets a cross.

Don’t expect to be perfect all the time:

People shouldn’t be too fixated on eating healthily 100 per cent of the time – aim for perhaps 70 per cent some of the time and 80 per cent the rest of the time.


Click here to download the 4 page fad diets PDF



Diabetes New Zealand website information including recipes, healthy food tips, information on the glycaemic index, shopping and reading food labels.


Heart Foundation’s Healthy Living website has pages on healthy eating and managing a healthy weight. The healthy eating page has links to the ‘Healthy Heart’ visual food guide, the Heart Foundation’s ‘Tick’ programme, and recipes.


Healthy Habit Exchange is a new Facebook app to encourage people to switch to a healthy habit i.e. switching from starting work on an empty stomach to having a good breakfast or swapping blue-top milk for green. www.heartfoundation.org.nz/healthy-living/healthy-eating/healthy-habit-exchange

Post your comment


  • What a lot of rubbish!...the arrogance and ignorance is breathtaking!..

    Posted by Maryanne McKay, 15/07/2015 1:26pm (2 years ago)

  • So lchf is a fad diet...and so is the current advice that we have been following for the last 40 yrs which told us to increase carbs and reduce fats for heart risk. Clearly both the heart foundation and diabetes associations are out of touch with current science. Firstly id like you to ask heart foundation to show scientific proof that shows saturated fat 100% causes heart disease which will be interesting to see and they might want to pass on to there American counterparts considering they are dropping both cholesterol and saturated fat as nutrients of concern for heart disease.....they won't be able to come up with any evidence is the answer to this.
    As for diabetes....type 2 diabetes is completely reversable once carbs and sugar are reduced. Both carbs and sugar convert to glucose most rapidly and when the body cant process the extra glucose in the system the liver and pancreas send the excess to the fat storage parts of our bodies. Its a shame that both heart and diabetes foundations are both heavily compromised by who financially supports them in either case by big pharma or big food industry. Its one thing to say EVIDENCE shows this it's another to actually back it up with true evidence. How about they put there money were there mouths are and release docs for all of us to see.....i bet they don't...itll be the tired old they know best and trust us.....pffft.

    Posted by Rob, 14/07/2015 12:01pm (2 years ago)

  • Articles like this perpetuate the mis-information on various Ways Of Eating(WOE). The Pro/Cons are extremely misleading and inaccurate.

    Why? Suggesting that various WOEs are unsustainable suggests that there is a vested interest in keeping our population eating foods(or taking drugs) that ensure on-going revenue for businesses that are starting to see the effect of people making better choices. Diabetes New Zealand and The Heart Foundation seem to be working very hard at protecting the very same businesses that produce the foods that (in the last 50 years) are making our population fat.

    So disappointed!

    Posted by Peter, 14/07/2015 9:38am (2 years ago)

  • The authors of this piece could perhaps do with a lesson in researching a topic. I will limit my comments to the Paleo section, though I can see errors in the other sections covered.

    The authors are quite wrong on a number of fronts. I suspect this comes down to reference the most extreme and narrowminded versions of Paleo they could find. This is the equivalent of someone finding fault with medical professionals and modern medical practice on the basis of Dr Oz.

    I can assure you that Paleo/Primal HEURISTICS for whole food eating patterns do not limit starches, including potatoes, kumara, yams, taro, et al. Nor do they limit dairy, legumes or even whole grains. What is encouraged is for people to find what works for them best. In practice, this means that some people discover they are not particularly grain (typically wheat) or dairy tolerant, and I see this frequently in my own practice. Where there are no individual issues with any dietary component, people are encouraged to include these in their overall diet pattern.

    The above has been the stance of the main proponents of a Paleo framework/template for many years now. However, authors, such as the ones here, seem to either remain ignorant of this fact, or choose not to cite these positions, possibly due to them not suiting the narrative the authors wish to convey.

    It is a pity research into these topics is so poor, and misinformation is continually spread. In the end it only reflects badly on the authors and their profession.

    Jamie Scott

    Posted by Jamie Scott, 11/07/2015 6:04pm (2 years ago)

  • I have used paleo/LCHF-type diets extremely effectively with my patients for both weight loss and as adjunctive treatment for a variety of chronic diseases, including type I and type II diabetes. Unfortunately the authors of this article do not seem to appreciate the pathophysiology of diabetes or ketoacidosis (which is NOT the same thing as ketosis). Using a whole foods dietary approach will never result in ketoacidosis. What it will do is reduce the requirement for insulin and/or oral hypoglycaemic drugs and result in improved glycemic control. Yes, caution is required with diabetics on those drugs capable of causing hypoglycaemia, but as long as a dietary change is made carefully in conjunction with a reduction in medication then it's perfectly safe. I have seen patients completely reverse type II diabetes and end up on no medication whatsoever. If this is a "fad", it's damned effective.

    Posted by Dr Greg Brown, 11/07/2015 5:49pm (2 years ago)

  • The statement below about LCHF diets is wrong about T2DM and ketoacidosis:

    "Not suitable for people with type 1 diabetes or people with type 2 diabetes on medication (other than Metformin) because of the risk of hypoglycaemia or ketoacidosis"

    Ketoacidosis is ONLY possible in the complete absence of insulin. Only Type 1 diabetics are susceptible because they produce no endogenous insulin. Virtually all T2DM patients produce some insulin except perhaps a very small percentage of late stage patients who should probably be classed as Type 1 because their pancreatic beta cells are burnt out.

    The fact is that T2DM is a a disease of carbohydrate intolerance. The first line treatment should be to reduce carbohydrates. LCHF diets have proven highly successful in the management of T2DM and in fact have been shown by many clinicians to normalize blood glucose and enable T2DM patients to reduce or eliminate metformin and even exogenous insulin in more severe cases.

    Any risk of hypoglycemia is easily managed by slow reduction of carbohydrates, monitoring of BG and slowly reducing drugs like metformin as the reduction in carbohydrates reduces hyperglycemia instead.

    Anyone who want to find out how good LCHF diets are for treatment of T2DM and how to implement them should read information by Steven Phinney, Jeff Volek, Eric Westman, Tim Noakes, Sarah Hallberg and Jason Fung,

    Posted by Kurt Lass, 11/07/2015 12:43am (2 years ago)

  • The article was incorrect* (see editor's comment) regarding LCHF diets and CHO. You are forgetting that dairy products and fruit/veg included in the diet have CHO's. While saying that some saturated fats are ok, they also advocate using healthy fats (ref. Dr Grant Schofield, AUT, NZ). He also discusses what might cause failure of the diet which is precisely what you state: not keeping to reasonable amounts of each food group. The truth is that we can overdo any eating habit.
    I'm also interested in why you would have to add multivitamins to a diet that is cutting down on simple CHO's and encouraging fruit, veggies, appropriate amounts of proteins?
    I have not had trouble adjusting to this way of eating. As with ordinary eating one has to find the right level for themselves. In addition, out of 21 meals a week, 3 are 'off'. So, in the end it is about rearranging, not excluding food groups.

    Let's be honest: It is the very Food Pyramid advocated by educated people since the 70's based on the FDA's assumption that fat must be bad for you and encouraging us to eat carbs that has been a very real factor in widespread obesity in the Western World. Here we are 40 years later trying to regain balance.

    Why not go to the website for Dr Grant Schofield and look at his 'What the Fat' book to get a balanced view of what this lifestyle change really is.

    EDITOR's RESPONSE: This article is based on advice from dieticians working for the Heart Foundation and Diabetes New Zealand. Nursing Review is happy to publish the comments of people who disagree with this advice but publishing them does not mean endorsement.

    Posted by LMM, 10/07/2015 11:02am (2 years ago)

  • So a hunter-gatherer diet is a fad because it eliminates man-made 'foods' whereas the 'healthy eating' guidelines recommend PUFA oils that have only been around about a century, so that's obviously not a fad?

    Posted by Cleethorpes UK, 10/07/2015 7:16am (2 years ago)

  • It was this information from so called "dietitians" , The Food Pyramid etc that caused me to need a triple heart by-pass operation and become a type two diabetic.
    Some may ask, "how do you know that was the cause?"
    Well, I am a person who wants to know why things happen.
    It did not take me long to realize that I had been given wrong information.

    By simply changing dietary and life style habits, I am now no longer diabetic, all my symptoms that I had , such as high blood pressure, memory loss, joint pain,diabetes and general weakness and tiredness have gone. At eighty one years old I am enjoying a life of gardening beekeeping and walking, which I am sure that had I believed the doctor who told me that diabetes can only be "managed" not cured,I would not be able to have. This same medical center has told me that I am no longer diabetic, with a message from the doctor "What ever you are doing, keep doing it!"
    What ever I am doing is,The LCHF diet!
    I have not taken any prescription drugs or advice from doctors or dietitians since dumping the medications in the bin and taken control of my own destiny..
    My only regret is, that had I known twenty years ago, what I have learned in the last five years, I believe that I would not have developed the problems at all!

    Posted by Arthur H Hazeldine, 09/07/2015 5:30pm (2 years ago)

  • I think this is a very useful guide and healthy eating tips are terrific. New Zealand has the third highest rates of obesity in the world (after US and Mexico), which is pretty shocking.

    When people need to lose weight, I can recommend using the 5:2 diet covered above, which many in my family have used with great success, and been able to maintain. It is relatively easy because you only have to think about energy intake 2 days a week, and using a (free) app like MyFitnessPal makes that simple. Focusing on keeping your calories down on those two days also helps train you into becoming aware of the energy content of lots of foods. Also, when you have had to be careful on two days, you really begin to appreciate your food more generally and don't want to binge and ruin it on the other 5 days. You can learn all about it for free on the website: http://thefastdiet.co.uk

    Posted by Maggie B, 03/07/2015 6:02pm (2 years ago)

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