Log in to your account

Not a member yet?

Subscribe now



Fad or fact: Diets dissected

Tempted to go vegan, try fasting or give up gluten? Not so fast. Dietitian Melissa Meier guides you to the best eating plan for you.

Regular readers will know Healthy Food Guide is no fan of quick-fix weight-loss diets. We focus instead on a more balanced approach to food because, to maintain your healthy weight over the long term, you need to find a lifestyle and a way of eating you can stick with for life.

Still, there’s no shortage of diets promising a magic bullet for all your health woes, from fasting plans through to keto and everything in between. So, here’s the good, the bad and the ugly of diets.

Low carb

First popularised in the 1970s by the book Dr Atkins’ Diet Revolution, low-carb diets are back in favour. The common thread is the dramatic restriction of carbohydrates, including bread, grains, pasta, legumes, potatoes and even certain fruit.

Low-carb diets are effective for fast weight loss because carbs are stored in your body with water, so most initial weight loss is actually just water. Restricting carbs will also reduce kilojoule intake, so eventually your body will start to burn fat.

+ The positives

You are likely to cut back on low-fibre, high-carb processed foods, such as cakes, biscuits, chips, soft drinks and pastries.

– The pitfalls

Excluding nutritious carb-rich foods, such as fruit, wholegrain breads, cereals and legumes, puts you at risk of missing out on the fibre you need to keep your bowels healthy and to feed the good bacteria in your gut. A low-carb diet can also lead to headaches, mood swings and low energy levels.

Try this

Choose high-fibre, low-GI carbohydrates, such as brown rice, wholemeal pasta, grainy bread and legumes, and make them just one-quarter of your plate. And leave fruit on the menu.


Touted as one of the healthiest in the world, the Mediterranean diet has a large body of research supporting it. Communities around the Med, following a traditional diet, enjoy lots of veges, fruit, whole grains, nuts and olive oil, plus an active, social lifestyle. They eat fish and white meats in moderation and, occasionally, red meats, processed meats, dairy and sweet treats.

The traditional Med diet is linked to a raft of health benefits, including lower risk of heart disease, obesity and even some cancers. A recent study found that even after age 65, following the Med diet could increase longevity.

+ The positives

The diet centres on plant foods and healthy fats and no food groups are banned. You can even enjoy red wine, in moderation, when eating and socialising with loved ones.

– The pitfalls

There aren’t any!

Try this

Use extra-virgin olive oilto sauté onion and garlic, as a base for salad dressing or to roast vegetables. Build your meals around veges, rather than treating them as a garnish.

Fasting (5:2)

When UK jounalist Michael Mosley’s 5:2 diet came on the scene in 2013, it was hailed the ‘biggest diet revolution since Atkins’.

Intermittent fasting is less about what you eat and more about when you eat, restricting intake to just 2100 kilojoules per day for two full days a week – then eating normally the rest of the week. There’s also 16:8, where you fast for 16 hours and, on your fasting days, have an eight-hour ‘eating window’.

Fasting has been associated with a variety of health benefits, including weight loss, improved diabetes management and even gut health, although the long-term implications are, as yet, unknown.

+ The positives

You don’t have to exclude any food groups when fasting and the practice can help you tune in to your body’s internal hunger cues. In some cases, it can help people ‘kick start’ weight loss.

– The pitfalls

Fasting can be unsustainable and hard on your social life, particularly the 16:8 fast. Also, if you’re pregnant, breastfeeding or have certain medical conditions, it’s best to avoid fasting altogether.

Try this

Practise listening to your body. Rate your hunger on a scale of 1-10, with 1 being absolutely starving and 10 being absolutely stuffed. Start eating when you reach a 3 and stop around 6 or 7.

Gluten free

Gluten is a protein found in wheat, rye, barley and oats.

Around 1 to 2 percent of New Zealanders has coeliac disease, meaning they have an abnormal reaction to gluten. Over time, serious complications can arise if a strict gluten-free diet isn’t followed. For the rest of the population, however, excluding gluten simply isn’t necessary. Pseudo-science has created many misconceptions about gluten, but research shows gluten-free products aren’t any healthier than those containing gluten.

+ The positives

If you have been diagnosed with coeliac disease, removing gluten from your diet enables your gut to heal and symptoms to improve.

– The pitfalls

Some on a gluten-free diet may have an inadequate intake of fibre, folate and calcium. In the long term, this will be detrimental to immunity, bowel function and general health.

Try this

If you suspect gluten may be an issue, speak to your doctor and a dietitian before cutting it out completely, as coeliac disease can’t be tested for if you have already excluded gluten from your diet. Coeliac New Zealand (coeliac.org.nz) has an online test to assess possible coeliac disease risk. Otherwise, you are better advised to leave gluten on the menu, even if you cut back on it.


The paleo diet peaked back in 2014, largely due to celebrity chef Pete Evans’ unwavering support of the hunter-gatherer style of eating. The idea is we should eat the way our cave-dwelling ancestors did.

Meat, eggs, seafood, nuts, fruit and veges feature heavily in the paleo diet, while grains, dairy and legumes are out, making paleo a low-carb diet. It also promotes high-sat fat coconut oil, but without the science to support the oil’s health claims.

Short-term studies of those following paleo diets show positive results: weight loss, better blood glucose levels and improvements in heart disease risk factors.

+ The positives

The emphasis on natural, unprocessed foods is a plus. Cutting out refined, processed foods, such as white bread, cakes, soft drink and junk food, is a vast improvement for many people.

– The pitfalls

Unless you have a specific allergy or intolerance, there is absolutely no reason to exclude whole grains, legumes and dairy foods from your diet. In fact, there are good reasons to include them.

Try this

Stick to a palm-sized portion of red meat. Aim to have two meat-free meals a week to boost your intake of legumes, such as chickpeas and lentils.


The flexitarian diet is vegetarian most of the time, meat-eater a little of the time – and it’s rapidly gaining traction.

Flexitarians aim to reduce their intake of meat to a few days or less a week and focus more on legumes, whole grains, fruit, veges, nuts and seeds.

Flexitarians reap the benefit of eating more plant-based foods, but don’t have to miss out on their favourite Sunday roast, all while reducing their carbon footprint. This dietary pattern has been associated with good weight management, reduced blood pressure and a lower risk of type 2 diabetes.

+ The positives

No foods are actually restricted on a flexitarian diet, it’s more about tweaking your intake of certain groups and focusing more on plant-based foods. It’s relaxed and balanced.

– The pitfalls

You may need to pay extra attention to your protein, iron and vitamin B12 intake, depending on how much meat you are eating and whether you’re replacing those sources with vegetarian alternatives.

Try this

Introduce meat-free Mondays – you can find plenty of healthy, delicious vegetarian recipes at healthyfoodguide.co.nz


Veganism excludes not just all animal flesh, such as meat or seafood, but also animal products, such as dairy, eggs and even honey. There’s plenty of evidence to support the health benefits of going meat free, including lower levels of ‘bad’ LDL cholesterol and reduced risk of certain cancers.

+ The positives

With the focus on plant-based foods, you’ll consume more fibre, along with other vitamins and minerals, compared with meat-eaters.

– The pitfalls

You may miss out on key nutrients, such as vitamin B12, iron, calcium and omega-3 fats. If you’re new to vegan eating, take the time to plan your menu and talk to your GP or get advice from a dietitian.

Try this

To ensure you meet all your nutritional needs, aim to include alternative proteins such as tofu, tempeh, legumes (such as peas, beans and lentils), nuts and seeds.


The ultra-low-carb ketogenic diet surfaced in the 1920s to treat children with epilepsy, reappearing in recent years as an extreme weight-loss tool. It aims to get your body using ketones from stored fat as its primary energy source, rather than glucose from carbs. You have to drastically limit many healthy foods, such as grainy bread, pasta, fruit, dairy and certain veges.

The diet encourages high-fat foods, such as butter, cream and fatty meats. Getting enough fibre can be an issue, and the diet may lack gut-beneficial prebiotic fibre.

+ The positives

It has been shown to be effective for children with epilepsy and may help with short-term weight loss.

– The pitfalls

Side effects can include bad breath and fatigue, and the low level of carbs can be hard to sustain.

Try this

You don’t need to ditch carbs to be healthy. Instead, try to swap heavily processed carbs for high-fibre whole grains, legumes, fruit and veges.

Which is healthiest?

Diets are nothing new. They have moved in and out of fashion for decades, only to re-emerge in a new guise. The best diet is the one you don’t even know you’re on. What’s important is that you find what’s best for you – your own individualised, balanced and flexible eating plan, one you can easily stick to and afford. People with the healthiest lifestyles don’t diet, they just enjoy food! Food adds enjoyment to your life while helping you stay healthy.

How to spot a fad

Here’s a crash course in spotting fad diets, so you can run the other way:

  • The diet cuts out entire food groups
  • The diet calls for very high intakes of a specific ‘superfood’
  • The diet promotes expensive products
  • The diet promises a quick fix
  • The diet is endorsed by celebrities.

Article sources and references

Date modified: 12 August 2019
First published: Jan 2019


Shopping list saved to go to meal plans