The Copernicus of the diet debate?
In his immense new tome, Gary Taubes challenges the conventional wisdom that too much cholesterol is making us ill and fatty foods are making us fat. Who knows if he’ s right, but it’ s refreshing to read such heresy.
A couple of months ago, during a trip to the Big Apple, I decided to try one of these quintessentially New York foods: a pastrami sandwich. And where better to buy such a thing than Katz’s Deli, on the Lower East Side?
I was in for a shock, however; I simply wasn’t prepared for how big it would be. I ended up defeated by this mound of smoked beef, which seemed to weigh at least a pound, trapped between two pieces of bread that seemed too thin to serve any purpose other than to hold such an enormous quantity of meat in place. One sandwich laid waste to my appetite for the rest of the day.
Dr Atkins, the most famous promoter of ‘low carb’ diets, would have been proud. He would have hailed my satiety as an illustration that a diet based on large quantities of protein and fat, rather than carbohydrate, is the best way to lose weight while avoiding hunger.
I thought of this episode while consuming another offering from New York: Gary Taubes’ Good Calories, Bad Calories (published in the UK as The Diet Delusion). Taubes would have made the late Dr Atkins pretty happy, too. He argues, in a nutshell, that it is the increasing level of carbohydrate in our diet that is making us fat. Carbohydrate-rich foods include starchy products like bread, potatoes, pasta and rice, or the sweet stuff like sugar (sucrose to be precise), and a more recent addition to mass-produced food: high-fructose corn syrup (HFCS).
Taubes argues that the introduction of these products into the Western diet has been the biggest change over the past hundred years, helping to explain both the rise in obesity and ‘diseases of civilisation’ like heart disease and type-2 diabetes. However, he also berates those who have promoted a low-fat diet as the solution to these problems, noting how fat is not really a problem in our daily diets. By shifting the balance of food consumption towards carbohydrates, this international experiment with diet has made us fatter and less healthy.
It sounds like the same old, same old. A writer with a bee in his bonnet about one particular factor that can explain everything. Taubes quotes approvingly the critic and essayist HL Mencken: ‘There is always an easy solution to every human problem: neat, plausible, and wrong.’ So it could easily be with Taubes’ ideas, too. Hence, Taubes goes to great pains to lay out the evidence that both calls into question other ideas about diet and disease and which supports a viewpoint which is pretty much entirely at odds with conventional dietary and health advice.
The cholesterol consensus
The theory that heart disease is caused by having too much cholesterol in our blood was devised and furiously promoted by Ancel Keys, a physiologist from the University of Minnesota who first achieved a certain fame by developing packs of mostly dry food for soldiers during the Second World War known as ‘K-rations’.
During a trip to Italy after the war, it was pointed out to him that while heart disease was an apparently increasing problem in the Western world, this was not the case in Naples. After travelling to the city with his wife, a medical technician familiar with the new procedure for measuring cholesterol, Keys concluded that it was the diet of the ordinary Neapolitan – containing very little meat – that was the key. Rich people ate more fat than the poor and were also more likely to develop heart disease.
Keys drew together further observations over subsequent years which reinforced his feeling that the consumption of fat led to higher cholesterol levels in the blood which in turn led to atherosclerosis – ie, ‘furry’ arteries. At first, his peers were unconvinced. For example, Keys had presented an analysis of six countries, which he said confirmed his thesis. However, when data from all the 22 countries where figures for diet and heart disease were available were taken together, Keys’ association between fat and heart disease disappeared. While the level of saturated fat in the diet does seem to be related to cholesterol in the blood, it is not at all clear that cholesterol is the villain that Keys painted it to be. In fact, a study as early as 1936 on New Yorkers who had met a violent death, as opposed to dying from a medical condition, found that cholesterol in these patients bore no relationship to the level of artherosclerosis found in autopsy.
The fat-and-heart-disease theory should have been laid to rest by a number of big research projects that reported in the early 1980s, most particularly the Multiple Risk Factor Intervention Trial (MRFIT), which encouraged a large number of middle-aged American men with high cholesterol to change their diet so as to reduce their saturated-fat intake and, therefore, their cholesterol. These test subjects were also encouraged to quit smoking and to treat their high blood pressure. Meanwhile, another large group of middle-aged men were left to their own devices. The result? Slightly more men in the low-fat diet group died than in the control group, but to all intents and purposes the results were the same.
Given that the low-fat group were also the ones getting help to quit smoking, the death rate for them should have been lower even if their diet had no effect. As it was, the effects of other lifestyle changes seemed to be cancelled out by the very low-fat diet we are all still told to eat. (For a lengthier critique of the theory that cholesterol causes heart disease, see The Great Cholesterol Myth, by Malcolm Kendrick.)
Given the failure to produce convincing evidence for the cholesterol theory, how has the idea of measuring and lowering our cholesterol – most notably by avoiding fatty foods – managed to maintain such an iron grip on the imagination of doctors and health advisers? Taubes notes a variety of key events, in particular the issuing of a number of key reports in the 1960s and 1970s, which gave the official stamp of approval to the cholesterol theory. Pulling together all the various incidents and individuals mentioned by Taubes, it is possible to provide a step-by-step account of how to turn dodgy science into ‘scientific fact’ with particular relevance to the day-to-day lives of whole populations:
- A researcher becomes obsessed by an interesting but ultimately misleading observation and produces a hypothesis;
- the researcher, and others persuaded by the theory, ignore evidence which tends to undermine the hypothesis;
- supporters of the hypothesis persuade someone with influence that the hypothesis is correct – it becomes ‘official’;
- anyone who disagrees is dismissed as having a conflict-of-interest, or treated as if their criticisms are tantamount to disloyalty because they could undermine interventions which have been agreed for the Greater Good;
- subsequent research will then tend to be reconciled, often unconsciously, with current programmes of prevention even if an objective view of the data would conclude otherwise.
These are just the kinds of criticisms that are made of other areas of science and public policy – for example, around climate change. In particular, the mobilisation of the forces of the state, healthcare, big business and the general public requires consensus. Science by consensus, however, may well distort the scientific process. As Francis Bacon noted: ‘In sciences that are based on supposition and opinion… the object is to command assent, not to master the thing itself.’
A bitter pill, sugar-coated
While this case study in the dangers of consensus is an illuminating read, the bulk of Good Calories, Bad Calories sets out to explain – over hundreds of pages – why carbohydrates may be the dietary villain of the piece in our war on chronic disease and obesity. And in place of cholesterol, Taubes points the finger at a new enemy within: insulin.
Like Keys, Taubes points to a number of observations that he believes call into question the cholesterol consensus and point to another explanation. For example:
- If diets high in saturated fat cause heart disease, why is it that some groups like the Masai in Kenya can eat high-fat diets and yet be apparently free of heart disease, type-2 diabetes, obesity, and so on?
- Why is it that low-fat, calorie-controlled diets of the kind which are standard advice to those wishing to lose weight are so spectacularly unsuccessful?
- Why has type-2 diabetes taken off in the Western world, particularly over the past 30 years?
- If obesity is a consequence of overeating or underactivity, why do reports that examine one or the other find little change in food consumption or activity over time?
- Even if obesity were a consequence of overeating, why would people persistently do so even after they felt satisfied?
- Are we morally degenerate, or is there something about how we eat today that precludes satiety?
Any attempt to summarise Taubes’ points will fail to do justice to the detailed collation of evidence contained in his book. While others have knocked off short, popular little books placing the blame for our increasing girth and its medical complications on all manner of factors (a good example is Greg Critser’s bestseller, Fat Land: How Americans Became the Fattest People in the World), Taubes isn’t simply interested in the intelligent lay reader. He wants to convince the professionals, too. He believes that excessive specialisation in research and medicine has meant that important breakthroughs in one specialty are rarely synthesised with those in other specialities, or even sub-specialities. As a science generalist, Taubes’ aim is to bring these different insights together.
It will fall to more knowledgeable thinkers than me to determine whether Taubes has a case. But for the rest of us, Taubes provides a simple blow-by-blow summary of his argument. Fat is not the problem – the problem is the effect that eating carbohydrates has on the production of insulin. Insulin controls the conversion of this carbohydrate into fat, and chronically high levels of insulin lead ultimately to heart disease and, because our bodies start to become resistant to the effect of insulin, to the development of type-2 diabetes.
The answer, then, is to cut down or even cut out those carbohydrates. The effect – if Taubes is right – should be weight loss (more specifically, fat loss) and a lower risk of some of these chronic diseases.
Time will tell whether Taubes will gain wider interest for his ideas and, indeed, if they’re correct. What seems abundantly clear is that banging on at entire populations to eat less and exercise more has been an utter failure in terms of reducing levels of obesity. Even if Taubes is barking up the wrong tree, reposing the question of obesity and chronic disease in terms of changes in the balance of diets might be a more fruitful avenue for research than assuming that great swathes of the population are simply too lazy or too stupid to change their wicked ways – especially when the current prescription, the reduced-calorie, low-fat diet, has been such a profound failure for so many people.
Rob Lyons is deputy editor of spiked.
The Diet Delusion: Challenging the Conventional Wisdom on Diet, Weight Loss and Disease, by Gary Taubes, is published by Vermilion. (Buy this book from Amazon(UK).)
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