NARRATION

There's a diet that seems to be changing people's lives for the better.

Gabrielle Brunsdon

I've lost all this weight and I feel better and my heart feels better and my blood sugar is normal.

Professor Tim Noakes

If you followed this diet, we could reverse obesity and type 2 diabetes.

NARRATION

Even elite athletes are rethinking the way they eat.

Shane Watson

Now it's just so much easier to control my weight.

Dr Peter Brukner

LeBron James, Carmelo Anthony and Kobe Bryant are three of the biggest stars in American basketball, are now on low-carb eating.

NARRATION

But is this just another fad?

Associate Professor Tim Crowe

What sells books is a new solution to our weight loss problems and carbohydrates are the perennial villain in this case.

Melanie McGrice

And a lot of these low-carbohydrate diets that people are following fad diets and people aren't meeting all of their nutrition requirements. So that can actually be quite dangerous.

Dr Maryanne Demasi

In this special edition of Catalyst, I investigate the science behind the low-carb diet. Should everyone be on it and what are the risks?

NARRATION

In the '70s, dietary guidelines around the world promoted the food pyramid, which recommended we reduce fat and eat a lot more carbohydrate.

Professor Katherine Samaras

It was recognised that carbohydrates were a cheap energy source and still are. And as a cheap energy source, they've made it into our diet.

NARRATION

Reducing fat became the cornerstone of health advice for the next 40 years.

Associate Professor Tim Crowe

As a nutritionist, I'm willing to wear some of the blame here, that just that the simple 'eat less fat' message hasn't worked very well. What happened was people ate less fat and replaced it with a lot of processed carbohydrates, particularly sugar.

Dr Peter Brukner

We're all having far too many carbs, in our soft drinks, in our fruit juices. Processed foods is full of carbohydrates because when they took the fat out of food, they took the flavour out. So they had to replace it with something.

Professor Tim Noakes

What they deny is that humans have no requirement for carbohydrates.

NARRATION

Controversially, some doctors are now proposing we flip the message. Instead of reducing fat, we need to reduce carbs.

Professor Tim Noakes

We're just collecting information, we're collecting the people.

NARRATION

South African Professor Tim Noakes believes the surge in carbohydrate consumption has contributed to the obesity epidemic. Why? Because carbohydrates stimulate a hormone called insulin, which increases the body's fat stores.

Professor Tim Noakes

The role of insulin in the body is to build fat. So if you're consistently eating every three hours carbohydrates, what happens is you consistently have an elevated insulin concentration in your blood. What that does is it drives the excess carbohydrate into the fat cells and the fat cells now cannot release the fat. The brain somehow interprets this as that you're starving. So three hours later you have to go and eat again. And that is why you get this repetitive eating behaviour in people who are eating carbohydrates.

NARRATION

Of the three dietary macronutrients, carbohydrates are the most potent stimulator of insulin.

Professor Tim Noakes

When you eat fat, you get essentially no insulin response. When you eat protein, you get a moderate response. When you eat carbohydrates, you get relatively higher responses. Many people get the wrong impression of this diet. It's not a high-protein diet for that very reason we don't want all that insulin secretion from a high-protein intake. However, you do need enough protein to sustain your muscle mass and also to prevent hunger. But predominantly it's a low-carbohydrate diet, that is the key.

NARRATION

Professor Noakes says the low-carb diet with moderate amounts of protein helps you lose weight because it reduces cravings and makes you feel fuller for longer.

Professor Tim Noakes

What this diet does is it's high in fat and protein and that satiates your brain and reduces your hunger. That is the key to this whole process because if you can reduce your hunger, your calorie consumption goes down.

Melanie McGrice

Thanks for coming in today. Have you seen a dietician before?

Client

No, I haven't.

Melanie McGrice

OK.

NARRATION

Spokesperson for the Dieticians Association of Australia, Melanie McGrice, agrees that a low-carb diet can help with weight loss.

Melanie McGrice

Somebody who I would consider putting onto a lower carbohydrate-higher fat diet might be somebody who needs to lose weight quickly, possibly if they're going to have surgery or they might have been able to do exercise in the past, but now they've put on too much weight and they just need to get some fast weight loss off so that they can go and get back into exercise again. So there's certainly times and places for a lower carbohydrate-higher fat diet. But what we need to remember is that that's not a solution for everyone.

NARRATION

While dietary carbohydrates are normally the main source of fuel in the body, they're not an essential macronutrient. If you remove them from the diet, the body can switch to burning fat for energy instead.

Professor Tim Noakes

Humans have absolutely no requirement for carbohydrate, not one gram do we require. Whereas there are essential fats and essential proteins which we cannot generate in our body. We have this fabulous liver that produces as much glucose as you require.

NARRATION

He says the optimal level of dietary carbohydrates will depend on how well your body processes them - some people metabolise them better than others. Low carb advocate, Dr Steve Phinney says many people are actually unaware that they're 'carbohydrate intolerant'.

Dr Steve Phinney

Carbohydrate intolerance is associated with some physical findings such as fat carried around the middle. It's associated in people generally if they have a strong family history of type 2 diabetes, what we call pre-diabetes or metabolic syndrome, we have people who generally are severely overweight, and there's some other conditions such as polycystic ovary syndrome in women, that is, they may not be overweight, they may not have diabetes, but is very responsive to carbohydrate restriction.

NARRATION

Professor Tim Crowe, a nutritionist from Deakin University, is concerned that this diet will eliminate healthy food groups.

Associate Professor Tim Crowe

A very extreme low-carb diet can be quite restrictive. So it cuts out a lot of foods, particularly a lot of wholegrain foods. And even fruit, that has to be cut out as well. These are really good healthy foods that we know reduce the long-term risk of chronic disease.

Dr Steve Phinney

For many people, wholegrains are an excellent source of energy and a healthful food. But when people become more insulin resistant, they have a difficult time disposing off those carbohydrates. We're not saying get rid of wholegrains in the diet, we're just saying reducing them in the most vulnerable fraction of the population that can't tolerate them.

NARRATION

But what about athletes? It's always been assumed that carbs are an essential fuel source for exercise. Professor Noakes has spent years as an exercise and sports scientist, preaching the benefits of carb loading before a big race, even published it in a widely popular book called the Lore Of Running.

Professor Tim Noakes

I spent 33 years of my life telling athletes that they must carbohydrate load, which meant that for the last three days before a marathon, you should eat 700 or 800g of carbohydrate. And I was the first in the world to produce these GUs that people lived their races on. So if you go to the Ironman, you'll see people taking GUs every half hour or so. So myself and Bruce Fordyce, who's the great South African ultramarathon runner, developed that product and I apologise because that was completely wrong.

NARRATION

He says in explosive events when you need a fast fuel source, then carbs will help. But for endurance athletes, you can last just as long by burning fat for fuel.

Professor Tim Noakes

Once the event lasts two or three hours, I don't see any advantage to carbohydrates, and then increasingly you'll burn fat. The more fat you eat in your diet, the more adapted you are. You can burn an enormous amount of fat if you're an elite athlete and easily cover really good performance running very fast, but you have to become fat-adapted.

NARRATION

A pioneering study on the performance of cyclists who were fat-adapted was done by Dr Phinney.

Dr Steve Phinney

My initial study on athletes done 30 years ago involved five bike racers who we controlled in a metabolic ward, fed them their usual diet for a week and tested their peak aerobic capacity and their endurance time to exhaustion.

NARRATION

The cyclists were then fed a very low carb-high fat diet for four weeks and their performance was retested.

Dr Steve Phinney

What that study demonstrated was if you give people at least four weeks to adapt, they come all the way back to their previous levels of performance and are able to do that in the absence of carbohydrates, and the reason they can do that appears to be because ketones replace much of the body's requirement for glucose.

NARRATION

Ketones become the alternative fuel source. They're produced when fat is being burnt for energy, and can be measured in the blood or urine. In this state, the person is said to be in ketosis. But are there risks?

Associate Professor Tim Crowe

Ketosis, we know the people that follow these diets in short term experience fatigue, lethargy, constipation. But ketosis, long term, we don't know if it causes any serious problems such as renal problems and so on. At the moment it seems to be fairly safe.

NARRATION

Dr Phinney has no doubt that burning fat for energy instead of carbs gives endurance athletes the winning edge.

Dr Steve Phinney

For athletes attempting to do prolonged endurance performance, if their body can be trained to use that fat as their predominant fuel, that fuel tank is more than ten times as big as the carbohydrate tank. That's why we see the ultra-endurance athletes not just winning races but setting records on low-carbohydrate diets.

Associate Professor Tim Crowe

Endurance wise, it actually makes sense to be using fat for your fuel tank, which is good for many hours, but when you need that high-power output to sprint to the finish line or to ride up the hill, as an athlete you actually fall behind, because that's when your body needs carbohydrates for maximum energy output and you don't get that.

NARRATION

Low-carbohydrate diets are naturally higher in fat.

Dr Maryanne Demasi

We've been so conditioned to fear fat that making it a large component of your diet is hard to wrap your head around. It certainly was for Australian cricketer Shane Watson.

Shane Watson

Everyone that had educated me about the way to eat and eat a low-fat diet meant that I had a fat phobia. I cut all the fat off my chicken, my meat, my bacon, everything. So I stayed away from butter, from cheese, stayed away from nuts, only a little bit of avocado, all the foods that are high in fat and high in energy. But in the end I was always very hungry because I was cutting all the fat out of my diet and was just loading up on carbs. Within an hour of eating I was always very hungry.

NARRATION

It took the personal experience of Australian Cricket Team doctor, Peter Brukner, to open Shane's eyes to a new way of eating.

Dr Peter Brukner

I had just turned 60, which was the age my father had developed type 2 diabetes. I was overweight. So I tested all my bloods before I went on this diet and then went on the diet for 12 weeks, lost 12kg. Easy as you like, eating low carb, high fat. So the old way our parents used to eat, you know, eggs and bacon, and butter and cream and milk and all those things that had been forbidden for 30 years, and stopped eating all the sugary things and pasta and rice and bread, all things that I've been eating and the weight just fell off. I was enjoying my food, I felt fantastic, my exercise capacity increased and I got to the end of that and I just couldn't believe it. Soon after that I went on tour, I had restarted my job with the cricket team, and the guys would be coming up to talk, 'Hey, what's happened?' Some of them in particular, Shane Watson and Mitchell Johnson, got very interested in the whole idea and decided they wanted to have a crack.

NARRATION

For the next 18 months, Shane went on the low-carb diet, while Dr Brukner monitored him closely.

Dr Peter Brukner

So your blood pressure is 133 over 66, which is excellent.

Dr Maryanne Demasi

Peter, how have Shane's medical records changed since being on the diet?

Dr Peter Brukner

Shane's always been one of these players who, despite high levels of exercise as an elite athlete, has always had a weight problem. Previously, the only way he could do it was really to starve himself. But since he's gone onto this diet, he's able to eat well, eat a large amount of saturated fat, his weight has been good. His skin folds, which is the way we measure the body fat - we measure that regularly in all the players - his skin folds have come down, so his body fat has come down. He's maintained his muscle mass. So he's also enjoying his food a lot more, he's much less grumpy than he used to be when he was dieting, and generally I think it's been a real positive thing as far as his wellbeing goes.

Shane Watson

My energy levels throughout the day have certainly improved, there's no doubt. Leading into a break, like lunch or tea, I'm certainly not as hungry as what I was. So energy's spread out really nicely throughout the whole day.

Dr Maryanne Demasi

When I first heard about restricting carbohydrates, Atkins Diet came to mind. How is this different to Atkins?

Dr Peter Brukner

Look, it's fairly similar. Atkins was low-carbohydrate. Atkins probably didn't emphasise the fat as much. So they probably had higher protein and not as much fat. I think the fat is really important. It's sort of hard to get your head around the fact that, you know, the more fat you eat, the more fat you lose. That's a very difficult paradigm. So there's a lot of people out there who struggle with that.

Professor Tim Noakes

The only way this is slightly different from Atkins is we we promote vegetables. Atkins wasn't really keen on vegetables, but his principles were the same - it was to cut out carbohydrates.

Dr Maryanne Demasi

Often when we hear about fat, it conjures up images of deep-fried chips and highly processed foods full of unhealthy trans fats. Well, this is different. It's real food full of natural fats, like coconut, cheese, eggs and fatty meats, even good old-fashioned butter.

Pete Evans

The best thing about this way of life is you don't have to calorie count, but...

NARRATION

Celebrity chef and vocal campaigner of low-carb diets, Pete Evans, says cooking with fat gets the best results.

Pete Evans

We know this, chefs know it - fat equals flavour. How good is that? We've got animal fat, and here we've got duck fat. But you could use beef tallow which is the fat from a cow. You could use lard, which is fat from a pig. You could use butter from the cow...

Dr Maryanne Demasi

All the things we've been told not to eat.

Pete Evans

Exactly. And my favourite, coconut oil, which is absolutely fantastic. * And you can eat it by the spoonful.

Dr Maryanne Demasi

I see bone marrow and liver, these are rather old-fashioned cuts of meat. We tend to go for the lean steaks nowadays.

Pete Evans

Yeah, exactly. What's interesting is our great-grandparents, they would've been eating marrow, heart, liver, brains, all of that because nothing ever used to go to waste. Because No.1, it's cheap. No.2, it's absolutely delicious and No.3, it's the most nutritious part of the animal that we can work with.

NARRATION

When restricting dietary carbs, people end up eating more fat, often saturated fat, which as been implicated in the development of heart disease.

Shane Watson

The first question I asked him was what about my arteries? Aren't I just gonna...? Isn't that fat that I'm eating just gonna go straight up and clog my arteries? And he made it very clear that that certainly wasn't the case.

Dr Maryanne Demasi

One of the concerns is that the diet is high in saturated fat which we're told raises cholesterol and causes heart disease. Are you concerned about Shane's cholesterol?

Dr Peter Brukner

Not particularly. In Shane's case, the HDL cholesterol, the so-called good cholesterol, has gone up. The triglycerides, which I think are probably the most important component, they're carbohydrate-driven, and they have not surprisingly gone down significantly. So I think he's in much better situation now than he was prior to this diet.

Professor Tim Noakes

One of the great myths of heart disease theory is that you eat saturated fat and somehow miraculously goes from your gut and plugs your coronary arteries.

Dr Peter Brukner

Saturated fat is not bad for you, we know that now. There is ample evidence that saturated fat is not the bogey it used to be. It's a great source of energy.

NARRATION

In the last decade, the medical literature has cast out over the link between saturated fat and heart disease. Recently, this widely circulated article in Time magazine questioned the controversial science of saturated fat and those organisations that say it's unhealthy.

Dr Maryanne Demasi

We approached the National Heart Foundation for an interview, but they declined to comment on camera. Instead they issued a statement saying that they still recommend we reduce our saturated fat intake and replace it with unsaturated fats found in foods like nuts, oily fish and vegetable oils.

NARRATION

The Heart Foundation's Tick program recently came under fire for endorsing foods that are low in saturated fat but high in sugar, like Honey Cheerios. Now, 25 years on, the Foundation recently announced they're reviewing their Tick program. This comes shortly after the Canadian Heart and Stroke Foundation said they were scrapping their Tick program, their CEO admitting that public criticism played a role. Some nutritionists say these diets are too difficult to follow.

Associate Professor Tim Crowe

All diets fail because they're prescriptive and they go against our normal eating habits. And the more restrictive they are, the harder they are to follow. It's really hard to give up bread, pasta, rice, things we really love. That's what you have to say goodbye to in a low-carb diet. So most people, eventually they will start reverting back to their old lifestyles and they will be back to square one, ready to soak up the next fad diet that comes along.

NARRATION

Pete earns a living by sharing his passion for low-carb recipes.

Pete Evans

What we've got here is a basic spaghetti Bolognese without the pasta. We used zucchini instead. And the Bolognese itself is full of nose-to-tail, basically. We've got some marrow in there, we've got some liver, we've got a little bit of heart and of course some beef mince from grass-fed cattle.

Professor Tim Noakes

And it tastes so good because it's so nutrient-dense. 'Cause, you know, people are always fighting this argument that food like this, because it doesn't contain grains, must be nutrient deficient. Because it has liver in it, it would be far more nutrient-dense than anything that was grain-based.

Dr Maryanne Demasi

Now, we know there's no one-size-fits-all approach when it comes to diet. However there is scientific evidence to suggest that a large proportion of the population with obesity or diabetes would benefit from restricting carbohydrates.

Dr Peter Brukner

These people don't metabolise carbohydrates well. That's what diabetes is, it's a failure to metabolise carbohydrates. Yet we've traditionally given these people high-carbohydrate diets. I mean, it just does not make any sense at all. I think both in the treatment but also in the prevention of type 2 diabetes. If we reduced the amount of carbohydrates in out diet, we will have a massive impact on type 2 diabetes, which is in epidemic forms.

Dr Steve Phinney

If somebody has lactose intolerance, they don't tolerate milk sugar, we tell them not to drink fresh milk. So if people don't tolerate carbohydrates, why shouldn't we tell them to reduce their carbohydrate intake to the level where it no longer causes them problems? This diet is really not necessarily for everyone, because there are many people who can handle the carbohydrates. It's only some people with insulin resistance and diabetes for whom it's an immediate problem and for whom they get immediate benefits.

Gabrielle Brunsdon

When I was told by the doctor that my blood sugar levels were really, really high at 14.7 fasting, that I would need a specialist for my liver, it was that moment that I felt my life was out of control.

NARRATION

Gabrielle sought the help of Melbourne GP Dr Zeeshan Arain to manage her type 2 diabetes.

Dr Zeeshan Arain

When Gabrielle first came in, she was very keen not to have medication and to try and reverse this or manage it as best she could with lifestyle measures. So I offered her the opportunity to go on a well-formulated low carbohydrate-high fat diet.

Dr Maryanne Demasi

What exactly did you instruct Gabrielle to eat?

Dr Zeeshan Arain

Basically I was quite prescriptive in what I told her. I said I want you to eat plenty of natural fats, so cook in butter, coconut oil, use olive oil. Don't go for the lean meat, go for the fatty cuts, lot of egg, dairy if you can tolerate it, but more so the high-fat dairy. So double cream, butter...

Dr Maryanne Demasi

All those things we're told not to eat.

Dr Zeeshan Arain

That's right.

NARRATION

Under strict supervision, Gabrielle dramatically changed her diet. She stopped eating carbs from processed foods and began upping her fat intake.

Gabrielle Brunsdon

For the first 12 weeks, it was a very, very simple way of eating with vegetables. There was no fruit whatsoever because my sugar levels were really, really high of course. And meat. There was meat in there as well. It's wonderful not being hungry.

Dr Maryanne Demasi

No cravings?

Gabrielle Brunsdon

No hunger. There's no hunger.

Dr Zeeshan Arain

Over the last four or five months, when we tested her results, we found her to have not only a 10kg weight loss, but the most impressive indicator to me was her HbA1c, which is that long-term measurement, had gone down to 5.4, which is what the normal population would have that's not diabetic. The size of her liver, which was enlarged, 23cm, has gone down to 15, which is normal.

Dr Maryanne Demasi

My goodness, you must have been pleased with those results.

Dr Zeeshan Arain

Oh, fantastic.

Melanie McGrice

I don't believe that everybody with diabetes should automatically be going on to a low carbohydrate diet. People who have medical conditions such as diabetes, really should be going and seeing their accredited practising dietician for that personally tailored advice because people don't just come with diabetes, they come with a whole range of different, other medical conditions. They come from different backgrounds, they have different lifestyles.

NARRATION

Although treatment for diabetes should be tailored for the individual, endocrinologist Professor Katherine Samaras believes restricting carbohydrates and lowering calories is key for diabetics.

Professor Katherine Samaras

In my view, it seems counterintuitive to be asking people who have a deficiency in insulin and inability to produce enough insulin, or require medications to help them make insulin, to be eating so much carbohydrate. A meal that's relatively high in carbohydrate can often produce very high glucose levels and this is a problem.

NARRATION

Professor Samaras has been working with the Federal Government to lower the carbohydrate level of hospital food.

Professor Katherine Samaras

So this is what the average patient with diabetes in hospital today would have had for breakfast. Cereal, one slice of bread, the little bit of jam for that, some fruit and little bit of milk to put on their cereal. But what that amounts to when you actually calculate the carbohydrate content is equivalent to 14 teaspoons of sugar.

Dr Maryanne Demasi

So what changes do you want to see implemented in this kind of diet?

Professor Katherine Samaras

An alternative is to give people two slices of bread and an egg. It only has half the amount of total carbohydrate. So 7 teaspoon equivalents of carbohydrate versus 14. We know that if you have high glucose levels in hospital, you have worse outcomes and higher mortality and longer length of stay. All of these cost the community, they cost the families, they cost the Department of Health. We can simply improve that by just improving glucose control in hospital, and it seems obvious to all of us that changing diet is a fundamental path of improving the outcomes of people with diabetes.

Dr Maryanne Demasi

What's wrong with replacing these carbohydrates with low GI carbohydrates?

Professor Katherine Samaras

Low GI carbohydrates just refer to how quickly the glucose is released into the bloodstream. But the load, the total amount of carbohydrates, still has to be dealt with. In diabetes research, we're understanding more and more that you can wear out the pancreas by getting it to work extra hard. And so, in that regard, the load of the carbohydrate actually counts. The GI may actually just blunt the glucose excursion after people eat. But it's still asking the pancreas to work extra hard. And so lowering the GI doesn't necessarily make the best outcomes.

NARRATION

At this conference in Melbourne, health professionals gather to discuss the science behind a low-carb diet.

Dr Caryn Zinn

There are round about 27-28 randomised control trials and the low carb-high fat out-performs the low fat way of eating.

Dr Troy Stapleton

We know we're not doing very well with our current dietary recommendations for diabetes.

Ron Raab, OAM

If you wanted to design a regime, a diet, that produced the worst outcomes in type 1 diabetes, you have the current recommendations. There's new paradigms around. You find there's resistance, there's head in the sand. I mean, after all, people like me have been telling them what they'd been preaching for 30, 40 years was wrong.

NARRATION

A critical review of the literature suggested that low-carb diets should be the first treatment option in diabetes because of the consistently good control of blood glucose and the reduction, or elimination, of diabetes medication. Diabetes Australia is an organisation that supports people with diabetes. But some question their dietary advice to patients. They recommend low-fat meals based on high-fibre carbohydrate foods like breads and cereals, the very foods that raise blood sugar levels. Diabetes Australia declined to comment on camera, but issued a statement saying, 'The public discussion about diabetes should not be about 'diets'. There is no general diet and we should aim to have individualised, tailored advice' for people with diabetes.

Professor Katherine Samaras

The diet recommendations for people with diabetes are really quite old hat, and they haven't been revised or thought through well enough, given that we also have an epidemic of obesity that we're having to deal with. In the United States, the recent recommendations for people with diabetes actually promote a lower carbohydrate intake. I think we should be looking at that and adopting some of those philosophies and asking our patients to restrict their carbohydrate.

Dr Maryanne Demasi

So what would you say to people who think this is just a fad diet?

Shane Watson

I'd just say try it and see how much difference it makes to your life.

Dr Peter Brukner

To me 'fad' means non-scientific and there is plenty of science out there. Ultimately I have faith that my profession is a science and they will see the science and eventually come around to this way of thinking.

Melanie McGrice

I think it doesn't matter which side of the fence you're sitting on, whether you're going to be following a low carbohydrate diet or a higher carbohydrate diet, one of the key message everybody agrees with is the fact that we should be following a diet that has non-processed foods and lots of whole foods.

NB *Catalyst has removed the comment from Pete Evans where he describes coconut oil as a source of 'monounsaturated fat.'

Coconut oil is predominantly saturated fat, it contains only a small amount of monounsaturated fat.