The big fat debate over whether keto-style diets are right for reversing diabetes –

Keto choices: Fat bomb slice and other low carb options on the menu at a Taupō cafe.


Keto choices: Fat bomb slice and other low carb options on the menu at a Taupō cafe.

Something is going on. Lined up in the cabinet at a Taupō cafe are a bunch of keto options.

Keto “fat bomb” cream slice. Keto bacon and egg sandwich. Special of the day, vegan keto stuffed tomatoes and pumpkin – just 1.5 grams of carbs.

Mention a ketogenic diet – or even its milder cousin, the low-carbohydrate/high-fat (LCHF) diet – and the medical establishment frowns. They felt they had got past this kind of faddish nonsense with the Atkins diet back in the 2000s.

But Taupō has a switched-on local doctor and now a switched-on community. Dr Glen Davies at the Taupō Medical Centre has been pushing a low-carb approach to repairing diabetes and other chronic metabolic diseases for a couple of years now.

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And he says it has become a self-help thing. A citizen movement.

Taupō’s “Reverse Type 2 Diabetes” Facebook page has 1200 members, he says. A weekly support meeting can draw over 100 people. He doesn’t even have to explain how low-carb works any more.

“Taupō as a community has just adopted LCHF. Everyone’s talking about it. Whenever I eavesdrop on a conversation in a cafe, it’s all people discussing their macros.”

Getting the town talking: Taupō's Dr Glen Davies says 41 cases of diabetes and pre-diabetes have been reversed now.


Getting the town talking: Taupō’s Dr Glen Davies says 41 cases of diabetes and pre-diabetes have been reversed now.

For years Davies says he did the usual wrong things as a doctor when patients came in obese, pre-diabetic, and then eventually diabetic.

Tell them to try to lose weight by eating less, rather than questioning their macronutrient balance. Then watch as the diabetes drugs didn’t do much but suppress the symptoms, while the inevitable deterioration of type 2 diabetes mellitus continued.

But in 2017, a few things happened. Davies says that was the year of the great sugar tax debate – the call to push back on unhealthy soft drinks and other processed foods.

As it happens, that went nowhere. But at the same time, keto diets were becoming the trendy thing. And as a doctor, he was seeing the results.

“I had some patients telling me they had lost a phenomenal amount of weight. I mean like 40kg.”

Finally he had one guy – a retired software company owner – who had managed to reverse his diabetes after a bit of research.

“He came in, plonked a whole lot of books on my desk, and told me to read them.”

So from 2017, LCHF eating principles became part of his surgery conversation. And the proof has been in the pudding. Or at least the pudding his patients aren’t eating any more.

Keto deficient? Lots of carbs mean we don't spend enough time in the fat-burning zone.


Keto deficient? Lots of carbs mean we don’t spend enough time in the fat-burning zone.

Davies says he is now up to 41 cases of diabetes and pre-diabetes put into remission using a low-carb diet. You can imagine what that is like after years of thinking diabetes was a progressive one-way disease.

“Geez, the reward of seeing people turn their lives around is why we go into medicine. Now we’ve actually got this powerful tool that works, hopefully we’re going to see a whole lot of invigorated and excited GPs doing what I’m doing,” Davies enthuses.


What the low-carb approach preaches is that diabetes is a lifestyle disease, and so needs a lifestyle cure. But the question is whether the medical establishment yet accepts ketogenic diets – high on fat – as the right thing to be doing.

The theory behind keto is that the human body is designed to alternate between two distinct metabolic states – eating and fasting.

When food is coming in – we are eating and digesting – our bodies are tuned towards burning glucose for fuel and storing any excess as body fat that we can save for later.

Then when food is short for some hours – or even days, as would have regularly been the case for our hunter-gatherer ancestors – the body switches into its complementary mode of ketosis.

Our fat stores are broken down into fatty acids and then ketone bodies – small acetone-like molecules – which serve as our other natural fuel source.

So separate systems for saving and withdrawing energy.

The problem is that, since the 1970s, our dietary habits have changed. We both eat a lot more and graze all day long.

With diabetes, it is the carbs – the sugar and refined starches – that are the issue, because they stress our insulin regulation of glucose.

The pancreas has the job of pumping out insulin as a signal driving blood glucose into our muscle cells and fat stores. And when the flow of sugary and starchy foods becomes constant, it never gets a rest. The body never switches into its other mode of ketotic fat-burning.

Eventually, under the assault, the pancreas will crack. It can keep a lid on blood sugars for even a decade or two by churning out ever greater doses of insulin. But finally it fails and full-blown diabetes appears.

Prof Jeremy Krebs: Low carb works. But so can calorie-restricting high carb diets too.


Prof Jeremy Krebs: Low carb works. But so can calorie-restricting high carb diets too.

So a ketosis-favouring diet becomes the obvious way to heal the disease. Deal with the excess carbohydrate which is at the root of type 2 diabetes.


The situation is urgent. Everyone agrees with that. New Zealand is now the world’s third fattest nation and Ministry of Health statistics say 250,000 Kiwis suffer from diabetes – double the number of 20 years ago.

Even more worryingly, a quarter of the population is pre-diabetic. So on their way to the disease. In the pipeline as a health cost.

If a low-carb diet can fix people as easily as the people of Taupō seem to think, you would expect to be hearing all about keto from the ministry by now.

What does the science actually say? What is the expert opinion?

On the face of it, there is a ding-dong academic battle going on; a standoff between the nutritional old guard and the keto crowd. But more of a consensus could be emerging.

The argument revolves around the acceptable balance of macronutrients – carbohydrate, protein and fat – in the standard diet.

Otago University’s Professor Jim Mann represents the health establishment view. He is director of the Edgar National Centre for Diabetes and Obesity Research and also a leader of the Government’s current Healthier Lives research challenge.

Mann has been blasting away at the safety of keto diets for a good few years now.

He says the irony is that, when he was a young researcher in the 1970s, the recommended approach to diabetes was in fact a high-fat diet. They had thought of the “starve the disease” philosophy way back then.

“It was just eat as little carb as you possibly can. Have as much cream as you like.”

However, also in the 1970s, nutritionists were getting worried about cholesterol and its link to the biggest killer of all, coronary artery disease.

Mann says that led to the formulation of modern advice to steer clear of fat. A healthy diet needed to be half carbohydrate. The solid base of any meal should include plenty of starchy stuff like bread, potato, pasta and rice.

Protein would then make up 20 per cent of our daily calories, and fat the remaining 30 per cent – with the proviso that saturated fat was restricted to 10 per cent of the total.

Mann says his opinion hasn’t changed. Saturated fat is still a dietary no-no. That makes it a wrong thing to recommend even for diabetes or pre-diabetes.

But on the other side is keto fan Professor Grant Schofield, director of the Human Potential Centre at Auckland University of Technology (AUT).

Schofield says Mann is just out of date. Plenty of studies are now showing saturated fat is not the heart attack culprit it is made out to be.

Rather, it is insulin dysregulation from eating too much carb which is producing all the excess fat in our bodies and leading to deposits accumulating in wrong places such as our arteries. Sugar and starch are what increase our stroke and heart attack risk more.

Schofield says that means we should return to the sensible principle of just starving diabetes of its fuel.

With LCHF, the macro balance is flipped. The carb allowance is cut to 20 per cent, while protein stays at 20 per cent and fat is increased to be 60 per cent of the daily calorie intake.

Keto is the term for a more extreme version of this, in which carbs are under 10 per cent – a couple of bananas could blow your budget – and fat becomes over 70 per cent.

Schofield says if you eat enough fat, your body is forced to be ketotic, as fat is the only fuel you are giving it. And for those with diabetes or pre-diabetes, it can be a logical choice.

However, the fears about fat in the diet are so institutionally ingrained that any form of low carb still sounds like heresy to the old guard.

“To admit they’ve been wrong for these past 25 years – well, humans would rather not do that,” Schofield says.


Saturated fat is the sticking point. Yet get beyond that and more agreement begins to show.

Mann says his “high-carb” stance is often misunderstood. It is really about limiting fat and ensuring the body gets enough fibre. He wants people to eat lots of whole grains, such as oats, which are packed with that.

Schofield says LCHF should also stress the place for fibre and vegetables. It is just the concentrated starch – the grains and carb-heavy vegetables like potatoes, or too much sweet fruit – that have to be dropped from the diet.

He says low-carbers can eat a truckload of low-density carbs, such as broccoli or salad, and stay within their macro limits.

And both Mann and Schofield agree society as a whole needs to just stop eating sugar and processed foods. Doing this one thing in itself would take New Zealand a huge step towards defeating diabetes and obesity.

But what should people do once diabetes or pre-diabetes has hit? Is keto the bomb at that point?

Professor Jeremy Krebs, a Wellington-based endocrinologist for the University of Otago and Capital & Coast District Health Board, has been researching the dietary alternatives, including LCHF diets and intermittent fasting.

“My conclusion is there is no one single solution,” he says.

Krebs says low-carb does work. But then so does high-carb if it means that, in being more attentive to their diet – switching to whole foods and high fibre, cutting out sugary processed snacks – people begin to shed some weight.

It is internal abdominal fat – the fat that infiltrates our liver and pancreas – which is the main issue, he says. That is why our pancreases finally pack up and we get diabetes.

Any means of getting rid of that makes a difference. And the good news is that organ fat gets shed first.

So bariatric surgery – a gastric bypass operation – can reverse diabetes because patients cannot help but restrict their calorie intake and start unclogging their pancreases.

The same applies to crash diets. Newcastle University’s Professor Roy Taylor has been making waves with an 800-calorie-a-day liquid shake plan.

Krebs believes low-carb is mostly just another such story. “We did a study 10 years ago where we showed the weight loss achieved was purely due to energy restriction and nothing to do with keto fat-burning at all.”

Keto’s claim to being the sustainable diet because all its fat and protein is satiating is also dubious, says Krebs.

“There’s lots of evidence that the more extreme the diet, the less likely people are to be able to adhere to it in the long-term.” Boredom at repeating the same meals sets in.

Krebs says keto can produce good weight loss. The danger is if the public are sold on it as their only choice and find after a while they can’t continue. “People have to be realistic. What are you going to do next? What’s your next option?”

So the low-carb may be getting people excited because diabetes has seemed an irreversible disease. Their restrictive diets do work.

Yet in terms of framing official public health advice, it becomes more complex. Is ketogenesis really a specially effective tool? And how much of government action ought to be aimed at our obesogenic environment if we actually want to fix our national eating behaviours?

So lifestyle change is the key, Krebs agrees. However, it is not the right time to be dogmatic. Using what works best for the individual is the key, he concludes.