This Is What You Need To Know About A Low Carb High Fat Diet
Tim Noakes’ revival of a 150-year-old high-fat, low-carbohydrate Harvey Banting diet has been roundly condemned by the medical establishment. The controversy has turned Noakes into a best-seller. It’s good PR – but is it good science?
This is what happens on a low-carb, high-fat diet. First, you cut carbs and sugar. There are no complicated food charts or reading labels. You just skip bread and chips and pasta and sodas and pizza. This alone should reduce your daily kilojoule intake by as much as 20 percent.
The increased amount of protein may suppress your appetite further, making you feel full quicker, and will trigger a couple of other recalibrations. You get constipated. Your breath might start to stink.
Dropping carbs forces your body to look for alternative sources of energy – instead of glucose, it targets the glycogen stored in your liver and your muscles. This process makes you lose weight. You may also look and feel less bloated.
At the same time your liver starts breaking down stored fatty acids, producing a by-product known as ketone bodies. Ketosis (the formation of ketones – which are partly responsible for the bad breath) can also act as an appetite suppressant. Your kidneys flush out the high level of ketones in your urine.
Under these conditions it’s possible to lose several kilograms in a matter of days.
So far most of your weight loss is accounted for by body water – what doctors call “diet-induced diuresis”. You’ve peed it out.
Water loss peaks in the first week. Depending on the shape you were in when you started, if you continue to cut out all carbs and focus only on protein and fat (and providing your total energy intake stays below the amount you use) you’ll probably keep on losing weight without much effort – or without ever really feeling hungry.
This is a revelation.
Unlocking your secret body makes you feel like you’ve won something; the lottery and a tax refund and a bequest from a wealthy uncle all at the same time, like those dodgy emails.
Although everyone knows those things are too good to be true, right?
It’s been about three years since sports scientist Professor Tim Noakes came across a random email in his spam folder, promising him “effortless weight loss”. Acting on impulse, Noakes followed the thread and rediscovered a 150-year-old low-carbohydrate, high-fat (LCHF) diet practised by an English undertaker named William Banting. (It’s also named the Harvey-Banting diet, after the doctor who prescribed it.)
It proved so effective that Noakes – who lost 18 kilograms, started running faster marathons, and was cured of a host of chronic ailments – performed a startling professional about-turn. A long-time advocate of carbo-loading for athletes (notably in his iconic book The Lore of Running), Noakes began to question not just his own science, but almost the entire framework of what he understood as “healthy” modern nutrition.
His extensive reading and analyses of research on nutrition, heart disease, diabetes and other chronic health problems, led him to the conclusion that our diets were making us sick. And, somewhere between the science and his intuition, Noakes thought he had found the answer. He singled out carbohydrates as the prime culprit, responsible for everything from obesity to cancer. At the same time he believed long-vilified fats were actually the good guys, what our primitive bodies were designed to eat and metabolise.
Noakes offered his own body – and the bodies, the running and swimming times of prominent sportsmen who followed his new regimen – as proof. There was science, if and when it was required; but most important was Noakes’ word(s): “Trust me,” he said.
Although Noakes has taken pains to point out he’s not the originator of the Banting diet, his frequent public endorsement of its principles – and the subsequent publication of his best-selling (Banting-based) recipe book The Real Meal Revolution – has created a degree of ownership. It is, now, as much the “Noakes Diet” as anything else.
For many reasons, this has resulted in what can fairly be described as a cult of personality rather than pure medicine – to the extent that it is now almost impossible to interrogate the nutritional science of LCHF without it being seen as a direct attack on Noakes himself.
In interviews, Noakes has indicated that he has felt targeted by the medical community – physicians, dieticians, nutritionists – because, he says, his claims threaten them. He has upturned the fundamental tenets of their science and how they earn a living; his discovery challenges the stranglehold of the big pharmaceutical companies that fund doctors and institutes and associations, and the food economy based on selling ever-increasing amounts of added sugar and carbohydrates.
It’s tempting to buy in to this theory – that Noakes is the maverick; the only one brave enough to challenge The Man, take on the status quo.
Except that Noakes is the one with a brand and a book and a website and a massive following online; and the professionals who disagree with him tend to work, largely anonymously, in research and public health and aren’t trying to sell anything.
And, when you set personalities and the deliciousness of lamb chops aside, the science of LCHF is nowhere near as simple or miraculous as its advocates would have you believe.
How to eat
“The media, books, self-proclaimed experts thrive on claiming that dieticians and nutritionists propagate one ‘regime’ for all,” says Professor Marjanne Senekal, Head of Human Nutrition at the University of Cape Town.
Although Senekal says there will always be “those with particular ideas”, the concept of the 1970s-vintage “prudent diet” is now acknowledged to be outdated. “Current recommendations for [the] composition of a diet actually allow a lot of room for individualisation. The core message is to avoid any extremes – too much or too little, cutting out particular food groups.”
There is consensus on some things that should be limited or cut out altogether: added sugar, refined starches, trans fats, too much salt…
For the rest, the golden mean is to “eat a variety of foods, a mix of animal and vegetable sources [with a preference for monounsaturated fats or at least limited saturated fats], fruits, fibre-rich cereals” and “also to be physically active”, says Professor Salome Kruger from North-West University’s Centre of Excellence for Nutrition.
Physical activity and a normal body weight promote a healthy metabolism says Kruger. Within these parameters the body will easily tolerate [non-extreme] variations of lower and higher quantities of fat and carbohydrates, depending on individual preference – but, she says, this should never extend to completely cutting out fruit and vegetables.
The recommendations for people who are overweight are not terribly different (aside from the fact that if you are overweight, you “should try to lose weight”). “Some people find they lose weight on high protein, some on a totally balanced diet,” Kruger says. “All dieticians will be able to prescribe a diet that is mixed, where you can lose an equal amount of weight.”
This is a modest point, but an important one. Medium-term diet surveys (no extensive randomised controlled studies exist beyond two years) show that, while eating tuna and brown rice may not be quite as exciting as having an entire cheeseboard for dinner, provided you cut equivalent total kilojoules, weight-loss will be pretty much the same whatever “diet” you follow. What is significant is whether or not you can comply with a specific eating plan in the longer-term. Novel diets often present with high initial compliance and weight loss, but this drops off after several months as extreme exclusions become harder to maintain (or afford).
There’s a more complex caveat, too; individualisation is not just about preference but also about the person. There are potential and inherent risk factors both in who we are and what we eat.
Dr Celeste Naude, senior researcher at Stellenbosch University’s Centre for Evidence-based Health Care, says individualised nutrition treatment involves “a complete assessment of nutritional health, taking into account medical history, other medical conditions and medication, the individual’s weight, height, physical activity level – a total risk profile – as well as food preferences, income and other environmental factors. The approach to [an] overweight guy in his thirties with no other risk factors will differ from that of an overweight guy in his late forties who has had a heart attack and suffers from high blood pressure.”
There is a decisive difference between individualised and population level dietary guidelines. “Spreading the message of a ‘magic’ extreme diet on a population level could be potentially very harmful to some people.”
State of the nation
Recent estimates suggest nearly two-thirds of all South Africans are overweight or obese. Linked to this, South Africa is mirroring a global rise in chronic conditions associated with unhealthy weight gain. Diabetes is the seventh-most common cause of mortality in South Africa. Similar spikes are being documented with high blood pressure and high cholesterol. Non-communicable diseases are now responsible for as much as 35% of all annual deaths in South Africa – the same percentage as HIV.
The revised South African Food-Based Dietary Guidelines, updated in 2012, were specifically developed “to address existing public health problems in South Africa,” explains Naude. Population-level dietary recommendations were “based on the Medical Research Council’s (MRC) comparative risk assessment of the underlying causes of premature mortality and morbidity observed in South Africa in 2000.”
Of 19 risk factors identified by the MRC, nine “relate directly to nutrition, namely high blood pressure, alcohol harm, excess body weight, high cholesterol, diabetes, low fruit and vegetable intake, childhood and maternal underweight, vitamin A deficiency and iron deficiency anaemia.”
Two risk factors – physical inactivity and unsafe water or sanitation – indirectly relate to nutrition, and are also included.
This should give some indication that the relationship between food and health is far from linear.
“By focusing on single nutrients and nutrient types in isolation, we are ignoring the complexity of the role of diet in promoting health and preventing disease,” says Naude. “Nutrient intake should always be considered as part of our total diet that consists of a variety of different foods, rather than zoning in on a single nutrient or nutrient type in terms of an exact benefit or harm,” she says.
“Poor food choices are only one of the risk factors that contribute to the development of chronic diseases,” explains Senekal. “Genetics, physical activity, smoking, alcohol, other substance abuse, our physical environment, stress, other diseases, and the ageing process itself all play a role.”
But we are also eating too much – and that’s not because of our genes. Modern food has become incredibly energy dense, and portion sizes have gotten significantly larger.
“Agricultural advances, changes in economy and technology, as well as societal changes – our expectations and value systems – have created circumstances where the energy of the food supply frequently exceeds the opportunities for energy expenditure through physical activity,” says Naude.
Noakes’ personal research around weight, nutrition and wellness led him to conclude that the obesity and chronic disease pandemic wasn’t just a product of how much we were eating, but what we were consuming – in particular, the high proportion of carbohydrates and sugar in our diet.
Noakes has compared carbohydrates and sugar to cigarettes and heroin, and referred to society’s “addiction for easily assimilated carbohydrates” –something he says is compounded by public health recommendations to follow “heart-healthy” low-fat, high-carbohydrate diets.
In Noakes’ own case, he diagnosed himself as being “carbohydrate resistant” – saying his “biology is such that I am unable effectively to clear from my bloodstream, the breakdown product of ingested carbohydrate, glucose.” This, he explained, was part of a bigger picture that included an inherited predisposition towards adult-onset diabetes. Noakes was already pre-diabetic.
Related: The Tim Noakes Diet
For these reasons, Noakes believed his only option was extreme carbohydrate restriction – a diet that emphasised kilojoule sources from fats and protein, and allowed only fruits and vegetables with low carbohydrate content.
While he admitted the diet was “not for everyone”, Noakes stated it was “the only effective long-term health solution” for anyone who shared his biology – and that he believed many South Africans “might benefit” from it. In a 2012 interview with Men’s Health, he said: “You don’t have to listen to what I’m saying, just try it.”
Noakes has since developed diabetes.
FATS VS CARBS
Noakes also argued that the conventional wisdom associating high fat consumption with heart disease was “unsubstantiated dogma”. (He has subsequently declared that carbohydrates are also responsible for all cancers. “Cancer is a carb-dependent disease”, he stated on Twitter.)
Noakes’ statements in relation to heart disease were bought to the attention of South African-trained Dr Jacques Rossouw, who works in the Cardiovascular Science division of the American National Heart, Lung, and Blood Institute (NHLBI).
At the end of 2012, on a family visit to Cape Town, Rossouw was invited to take part in a debate with Noakes at UCT – on the topic of cholesterol as a risk factor for heart disease, and current dietary recommendations.
The debate didn’t go well for Noakes. Facing an audience made up largely of academics and health professionals, his theories were aggressively dismissed. Noakes later called it a “kangaroo court”, and reportedly suggested Rossouw had been flown out “by the Heart Foundation ‘and other bodies’ to silence him”.
While much of Rossouw’s presentation (which is available for download from UCT’s health faculty website) revolved around complicated technical discussions on cholesterol and coronary heart disease (CHD), the correlations Rossouw drew between diet, obesity and chronic ill-health painted a slightly different picture to that posited by Noakes.
Rossouw’s data clearly indicated that, “reduced intakes of total fat, saturated fat and cholesterol, and increases in unsaturated fats were associated with reductions in serum cholesterol and [reduced] risk of CHD”. In other words: eating less fat had a positive effect on heart health.
Rossouw’s data showed something else: in certain populations where low-fat, high-carb diets were introduced, this had little to no effect on overall obesity. In countries like the US, Rossouw noted low-fat, high-carbohydrate eating practices had long preceded the current obesity epidemic – by several decades – indicating “other factors were primarily responsible”.
Importantly, even as obesity kept rising, CHD rates continued to decline where populations had reduced intake of dietary fat.
Rossouw went even further and suggested that, no matter what combination of fat versus carb we ate, obesity rates in developed countries would continue to rise. Changing dietary guidelines in Sweden provided proof. For around 30 years (from the 1970s onward), Sweden recommended and practised a low-fat “modified Mediterranean diet” to address high rates of cardiovascular disease. In the early 2000s, Sweden suddenly switched to a high-fat, low-carb eating model. Under both regimens, obesity increased.
Something else happened, too. As fat intake increased so did Sweden’s serum cholesterol levels. “Swedish researchers do not yet know if this change reversed the previously declining CHD rates,” Rossouw told Men’s Health. “It will be interesting to watch this natural experiment. I would predict their CHD rates will start increasing.”
This is where it gets confusing again. Should we be more concerned about losing weight and eliminating the associated risk factors with being overweight or obese – as Noakes claims, “[t]he vast majority of people are overweight, and the only way they’re going to lose weight and become healthy is to eat more fat and less carbohydrates” – or do we focus on eating foods that apparently keep us healthy without the panacea of potential weight loss?
Rossouw says while it is important we “find ways to reduce overconsumption and increase activity levels to reduce obesity”, it is “even more important to identify and treat other risk factors. A diet high in animal protein especially red meat and processed red meat increases rather than decreases the risk of diabetes, heart disease, and cancer.”
Professor Kruger agrees that extreme high-fat diets will have a “significant effect on cardiovascular health, with a much higher risk of stroke and heart failure”.
There are also indications that following dietary extremes such as LCHF for many years may cause osteoporosis and kidney damage in some people. Recent research shows that eating large amounts of meat could change the microflora in our gut in such a way that it promotes chronic inflammation and even colon cancer. A high intake of cereals, whole grain, fruit and vegetables may have the opposite effect.
Kruger also notes that it’s “not possible or sustainable or environmentally friendly for everyone to switch to a high-meat diet. Having animals eat plant foods to produce protein for humans has a negative impact on the environment. There’s also a lot of pressure on sustainable sources of fish.”
We also need to consider the potentially much higher rand cost of a high-fat shopping basket compared to a more varied grocery list.
In the end, it’s perhaps about balance rather than absolutes.
It’s easy to reduce Noakes and his revolution to extremes: a “magic bullet” versus Russian roulette. But the consensus around what (and how) to eat is not as polarised as Noakes and others have suggested. The middle ground of “healthy eating” is surprisingly varied and accommodating; it’s just… boring. Safe. Like wearing your seatbelt and driving at the speed limit.
It’s always more tempting to live fast.