TUCK IN: Professor Grant Schofield and Dr Caryn Zinn with a platter of food suitable to eat on a low-carb, high-fat diet.

The epiphany hit when professor Grant Schofield was working between the tiny Pacific Islands of Kiribati and Vanuatu on a public health mission.

On Vanuatu he found most of the population were healthy and happy, living the way they always had, in isolated villages with minimal input from the outside world. On low-lying Kiribati, however, where the people rely heavily on foreign aid, nearly all the adults were overweight or obese. The children were malnourished. Rampant diabetes meant the hospital was amputating up to 20 limbs a week.

"I left Kiribati thinking, ‘there's no reason for optimism here'," said Schofield. "In public health, you're always positive, but I remember flying out on that plane and thinking, forget sea-level rise, these people have a much bigger problem."

The difference? The food. Specifically, the amount of carbohydrates. In Vanuatu, the people eat the same way they have for decades - on fresh produce they grow or catch themselves - mainly fish, vegetables and coconuts.

About 60 per cent of their calories come from fat, more than double the average New Zealand intake. There was very little carbohydrate, just a small amount of rice.

Meanwhile, on Kiribati, the islanders survive on a staple of cheap imports such as soft drinks, white rice, flour, sugar, tinned fish and instant noodles.

"That's when the penny dropped," Schofield said. "Two islands - one running on real food, the other on the cheapest energy available - processed carbohydrates. If you ever wanted evidence that processed carbohydrates damage humans, you should go to Kiribati and have a look for yourself."

It was that moment that prompted Schofield, a professor at the Auckland University of Technology's Human Potential Centre, to return to New Zealand and try a low-carbohydrate, high-fat diet for himself.

Instead of using bread, rice or pasta as a main energy source, Schofield switched to eating meat, fish and full-fat dairy products including cheese and cream, nuts, seeds, olive oil and fish instead, making up 80 per cent of his calories from fat.

The rest of his energy came from fruit and vegetables - with the occasional glass of wine allowed. A typical day would be a coconut cream smoothie with berries; tuna, cheese and celery for lunch; and grilled steak and broccoli sauted in olive oil for dinner.

"I first of all tried it because I thought it was going to be ridiculous," Schofield says. "But then I did some self-experimentation with a respiratory mask and found, hang on, there might be something in this."

That was last year. Now, after Schofield has tested his low-carbohydrate, high fat theory on athletes at the Millennium Institute of Sport on Auckland's North Shore and compared the results with those of 20 randomised, clinical medical trials world-wide, he not only believes that high-fat diets work, but that they could be the key to a healthier lifestyle - and the key to reducing diabetes and obesity.

"What we've been told is that if you eat fat, you get fat," he says. "But really it's just the same word."

He prefers to look at the science behind it, which he says "makes sense."

The best way to explain the science is using rodents. On his computer, Schofield brings up a picture of two white lab-rats cuddled together. One is a normal-sized rat. The other has the proportions of a small rugby ball, lying bloated and grotesque.

"OK," says Schofield. "So we've been told the only solution to obesity is if people eat less and move more - energy in, energy out - right? Well, while at one point that's true, I think that physiology is a much more complex system than that."

Basically, he says, there are some hormones in the body that have a lot to do with controlling weight. One is called leptin. It is secreted by your fat cells and helps the brain regulate eating - like an ‘off switch' saying, "I've had enough to eat".

Importantly, the obese rat has been bred so it doesn't produce leptin. Although it is fed the same as the normal rat, it doesn't know when to stop and would, if it could, literally eat itself to death.

The second hormone is called insulin, which is produced by the pancreas to manage blood sugar, or glucose. Insulin's job is to move the glucose around and get rid of it.

When we eat carbohydrate, creating glucose, says Schofield, insulin firstly rushes to the fat cells and turns the fat-burning ability off.

It tries to get glucose into the muscles to be used as energy instead. If that can't happen, it tries the liver, and if there's still no luck (because there's already too much glucose in the system) it stores those carbohydrates back as fats.

Now, if you're in good shape, Schofield says, your carbohydrate intake is unlikely to be stored as fat. However that's not the only issue.

The second problem is the insulin itself - particularly among those with Type II diabetes, who can produce insulin but are "resistant" to it, meaning even small amounts of glucose mean a lot of the hormone in their system.

The problem, Schofield says, is that excess amounts of insulin can block the all-important other hormone, leptin, getting to the brain.

"Essentially, you become like that rat who wants to eat and eat and eat," Schofield says. "It's not all about willpower here. Your physiology is working against you."

Therefore, Schofield says, the answer seems obvious. Restrict carbohydrate and you solve both problems - your body learns to burn fat for energy instead of carbohydrate and insulin levels get under control.

And it's not just for the overweight. In his initial testing, Schofield convinced Ironman Bevan McKinnon to go on the diet then took him into the lab.

They then assessed the proportion of fat to carb McKinnon was metabolising prior to and during the diet - by measuring the proportion of carbon dioxide and oxygen used during exercise.

Schofield found McKinnon was able to metabolise a greater proportion of carbohydrate after eating high-fat for 10 weeks, moving from drawing 80 per cent of energy from carbs to 80 per cent from fat after 10 weeks.

McKinnon said he felt better for the diet and - surprisingly - even his high cholesterol levels improved.

Another convert is Ironman triathlete Graham Brewster, who has been eating full-fat meals for a year.

"I am one of Grant's first guinea pigs. He sat me down and said, ‘look mate, how come you're training so much and are still fat?'."

Within months he shed 7kg, and has just 7.3 per cent body fat. "It's taken a bit of experimenting to get the right level of fuel for training but I feel better."

While the theory sounds straightforward in principle, and the results so far are good, there is a downside. Schofield's approach is completely at odds with the Ministry of Health's nutrition guidelines - which advocate lots of grains and vegetables, low-fat dairy and lean meat.

The Heart Foundation, which advocates a largely avoiding the saturated fats in meat and dairy products, says it too would be wary of a high-fat approach.

It has got the scientist offside with several high-profile health experts, including the University of Otago's human nutrition and medicine professor Jim Mann, who said there was absolutely no evidence that anyone should be on a long-term, very low carbohydrate diet.

Mann said in fact, some research had shown the "fad" of very low-carb diets (ie diets where carbs make up under 40 per cent of energy intake) had shown increased cholesterol levels - the biggest risk factor in terms of heart disease - in some countries.

"This approach is regarded as lunatic fringe," says Schofield.

"Some people think I'm crazy. And maybe I am. But in nutrition science, as in all other science, we must be prepared to change our mind on the basis of evidence. If we had it right already then we wouldn't have problems like obesity and diabetes."

Schofield has managed to convince some health professionals, including colleagues at AUT to join him in his quest.

He's also got a number of the staff onboard thanks to his relentless enthusiasm - at one point he would stroll through the office drinking cream to make a point - and public lectures held on the diet have so far packed out.

Dr Caryn Zinn, a dietician, is one of those on board with the approach and has begun to recommend it to her clients.

"On the whole people like this programme," she says. "They feel full. A lot of people say they feel like they were addicted to carbohydrates - which is probably true because sugar, as we know, is addictive."

Zinn says however, there are several obstacles to overcome. One problem is that people hear "high fat" and they think takeaways, which is wrong.

The second is whether it is feasible and affordable - given the relatively high cost of fresh food - for families long term.

"We will be looking at those who are overweight, who have diabetes - such as the pacific population," she said.

"We want to know if it's going to benefit those groups."

Zinn says while it is an uncoventional approach, she is comfortable recommending it and keen to do more research. "We just need to think - is this diet going to harm anyone? And the evidence says no."

Schofield gestures at the example plate of food on his desk - meat, cheese, avocados, nuts - and says, "How can this be bad for you? We're talking about the sorts of foods that people have eaten for 99 per cent of time they've been on earth. It's products that last for weeks and weeks that I would be more concerned about."

Zinn will now move on to further research with those who are obese.

Schofield, on the other hand, has bigger fish to fry. He wants to take on the public health experts and convince them his approach is worth a try.

After 20 years of supporting traditional messages, he now wants his colleagues in nutrition to consider that they could have it wrong.

"What we're doing isn't working. "Where we're at with what we tell people to eat nationally has been the ‘best guess' for a while. I would argue we can do better," Schofield says. His research is yet to be written up, but he says that's not the point.

This week, the number of obese adults hit 1 million. The number of people with diabetes in New Zealand is showing no point of abating.

"So yes we are moving fast," says Scofield, "but I say it's not fast enough."

CASE STUDY



Aucklander James Grey has been eating a low-carbohydrate, high-fat diet for six weeks. He started weighing 88kg and is down to 83kg.

"The biggest change was cutting out all the bread. And the fizzy drinks and fruit drinks as well. Other than that it wasn't much different - just eating more veggies, and being strict - having three meals a day with a snack. The first few weeks I was hungry and I think that's just because I was eating less, and being more controlled, but once I got over that it was fine. Now I'm full really easily and can last between meals. I was a little fatigued as well but that's gone too. I feel great!"

Sample meal plan

Breakfast: 2 egg muffins (made with eggs, vegetables-onion, spring onion, courgette, cheese)

Lunch: Large homemade seafood salad (2 cups), made with leafy greens, capsicum, tomato, carrot, avocado, pine nuts, olive oil-based dressing

Dinner: Chicken casserole: chicken, vegetables - (onion, mushrooms, pumpkin, leafy greens), made with cream, served on cauliflower rice (cooked in butter), glass red wine Snack: Small berry smoothie (frozen berries, coconut cream), piece camembert cheese

Fluid: lots of water, 2 full-fat coffees

Energy: 2570 Calories Carbohydrate: 66.1 (10 per cent of total energy) Protein: 128g (20 per cent of total energy) Fat: 179g (63 per cent of total energy)

For more information thenutritionsource.org