Wikipedia defines a false dichotomy as “a type of informal fallacy that involves a situation in which only limited alternatives are considered, when in fact there is at least one additional option”2. Leslie, the author of the Guardian article in question, wants us to believe there is some kind of a battle between sugar and saturated fat: “For at least the last three decades, the dietary arch-villain has been saturated fat” and now “Sugar has become dietary enemy number one.” What he neglects to mention is a simple third alternative: that both sugar and excessive fats may be problematic in the diet. In fact, if you look at the recommendations of those advocating a healthy low fat diet, they say with equal vehemence that we should also avoid processed foods and all added sweeteners. For example, the American Heart Association suggests:
Limit saturated fat, trans fat, sodium, red meat, sweets and sugar-sweetened beverages.3
In other words, we’re to limit saturated fat and sugar. To read this article, you’d think we have to choose one, and that’s just silly. There are hundreds of delicious dishes that contain very low amounts of saturated fat and/or added sugar, and in fact those practicing honest evidence-based nutrition advocate for eating precisely those foods5.
Appeals to Conventional ‘Wisdom’
People are confused about nutrition. The conventional wisdom is that we’re not getting sufficient protein, yet 97% of Americans get enough. And pretty much nobody thinks to ask about fiber, a nutrient which 97% of Americans are actually deficient in8. Suffice it to say, if we use conventional wisdom to base our nutritional decisions, we’re going to mess up (and most likely die of heart disease, like most people).
Leslie plays on our ignorance more than once. For example:
A low-fat diet effectively means a high-carbohydrate diet. The most versatile and palatable carbohydrate is sugar, which John Yudkin had already circled in red.
This plays on the conventional wisdom that carbs are bad, a trendy notion that travels the waves with little research to back it up22. In reality, not all carbs are created equal. It’s another false dichotomy; Leslie wants us to think that we must choose between a high-fat diet and a high-sugar diet, when in fact we can choose a diet that is low in both.
Another example is when he says “while humans have always been carnivorous, carbohydrates only became a major component of their diet 10,000 years ago, with the advent of mass agriculture.”
While it is conventional wisdom that we ate meat, the story is much more nuanced than that:
No paleontologist or anthropologist doubts that hominins ate meat – and, during the Ice Age outside of Africa, probably quite a lot of it – or that doing so shaped our evolution, but we’re not obligate carnivores who evolved in high latitudes. We come from the African tropics, and the ancestors from whom we inherited the plan for our digestive and masticatory traits are generally considered to have been largely frugivorous. Some australopithecine fossils even show evidence of grass consumption.18
Furthermore, even if we did eat meat thousands of years ago, that doesn’t necessarily mean it’s a healthy choice today21.
Nutritional guidelines story
Leslie specifically attacks the nutritional guidelines from the 1980s as a source for our obesity woes today:
In 1980, after long consultation with some of America’s most senior nutrition scientists, the US government issued its first Dietary Guidelines. The guidelines shaped the diets of hundreds of millions of people. Doctors base their advice on them, food companies develop products to comply with them.
The most prominent recommendation of both governments was to cut back on saturated fats and cholesterol (this was the first time that the public had been advised to eat less of something, rather than enough of everything). Consumers dutifully obeyed. We replaced steak and sausages with pasta and rice, butter with margarine and vegetable oils, eggs with muesli, and milk with low-fat milk or orange juice. But instead of becoming healthier, we grew fatter and sicker.
The nutritional guidelines issued in 1982 were indeed problematic, but not for the reasons Leslie implies.
T Colin Campbell is one of the aforementioned “senior nutritional scientists.” He has been a nutritional researcher all his adult life. He began his career thinking milk was the perfect food, but over time and lots of evidence, his perspective was tempered. Today he is a Professor at Cornell where he has the Center for Nutrition Studies named after him, and he promotes a whole-foods, plant-based diet that is low in both saturated fat and sugar24.
As one of the researchers who was on the dietary guidelines panel in 1982, Dr. Campbell’s perspective sheds light on what was really going on in those guidelines:
The focus on individual nutrients instead of whole foods has become commonplace in the past two decades, and part of the blame can be put on our 1982 report. […]
The nutrient that our committee focused on the most was fat. The first guideline […] recommended reducing our fat intake from 40% to 30% of calories, although this 30% goal was an arbitrary cutoff point. The accompanying text said, “[T]he data could be used to justify an even greater reduction. However, in the judgment of the committee, the suggested reduction is a moderate and practical target[…]” One of the committee members, the director of the USDA Nutrition Laboratory, told us that if we went below 30%, consumers would be required to reduce animal food intake and that would be the death of the report.
At the time of this report, all of the human-based studies showing fat to be related to cancer were actually showing that the popluations with more cancer consumed not just more fat, but also more animal-based foods and less plant-based foods. This meant that these cancers could just as easily be caused by animal protein, dietary, cholesterol, something else exclusively found in animal-based foods, or a lack of plant-based foods. But rather than wagging the finger at animal-based foods in these studies, dietary fat was given as the main culprit.23
There’s a lot wrapped up in this account, and I would encourage anyone who wants to gain a broad understanding of nutritional research to actually read Dr. Campbell’s book, The China Study. But the point here is that the vilification of fat is an error, in a way, but not in the way that Leslie implies. The main issue is the focus on individual nutrients, rather than whole foods (you know, the stuff we actually eat). High fat content is really more of a symptom of a poor diet than a cause. It’s a signal that we’re probably not eating enough plants.
So what sounds like a conflict, some kind of epic struggle between the forces of high fat and high sugar, in fact fits perfectly with the science. There is no contradiction here. The science advises:
- Focus on whole foods. That means avoid processed junk, added sweeteners, trans fats, and oils.
- Focus on plant-based foods. That means avoid foods of animal origin which contain lots of saturated fats and cholesterol, as well as trans fats and excessive animal protein.
Of course, if we do this, we’ll probably end up eating significantly less fat overall, and less sugar. But then the article gets boring! Sorry..
The National Heart, Lung and Blood Institute decided to go all in, commissioning the largest controlled trial of diets ever undertaken. As well as addressing the other half of the population, the Women’s Health Initiative was expected to obliterate any lingering doubts about the ill-effects of fat.
It did nothing of the sort. At the end of the trial, it was found that women on the low-fat diet were no less likely than the control group to contract cancer or heart disease. This caused much consternation.
What he neglects to mention was that this study did not lower fat levels very far, as pointed out by the Harvard School of Public Health. Women on this study started at 38% calories from fat, aimed for 20% calories from fat, and only actually made it to 29%15. It is common in these studies to say that a “low-fat” diet is 30% fat or lower. Yet the research on fat intake and health outcomes shows that health benefits accrue to plant-based populations eating much lower fat, down around 10% or 15%23. So this study tells us very little about what would have happened if the women had actually gone on a healthy plant-based diet.
When he cites the Oxford study of heart disease which “shows an inverse correlation between saturated fat and heart disease,” he neglects to mention that in the populations that get almost no heart disease, cholesterol levels are way lower16. Why would we want to accept the heart disease risk level of any of the Western countries featured (around 1 in 2), when we can reduce our risk to 1 in 1000 with a healthy plant-based diet and lifestyle?
Perhaps the most important part of all this is that we get the story straight. From reading this article, one gets the impression that there are a handful of highly institutionalized scientists who won’t let go of their arcane notions of what healthy eating looks like.
The first place the narrative goes awry is when he claims:
The most prominent recommendation of both governments was to cut back on saturated fats and cholesterol (this was the first time that the public had been advised to eat less of something, rather than enough of everything). Consumers dutifully obeyed.
Like most of this article, there are no citations, so who knows where he got the idea that consumers actually cut back on saturated fats and cholesterol. But if you look at USDA data, total fat intake did not change in any significant way since the recommendations came out26:
Perhaps the type of fat intake has changed due to an increase in vegetable oil consumption, but if that’s the case, then we’re not doing what the research says to do, and so it makes sense that we’re not seeing the improved results. Studies have shown that when we actually adhere to a healthy plant-based diet, the improvements to heart health are undeniable25.
Food Industry Influence
Another omission here is the significant influence of the food industry. It has been shown that if a nutritional study was funded by the food industry, it is 7.6 times as likely to come to an industry-favorable result11. This is a critical part of the narrative which is missing from Leslie’s story.
And perhaps for a reason. Leslie states:
Repeated attempts to prove a correlation between dietary cholesterol and blood cholesterol failed. For the vast majority of people, eating two or three, or 25 eggs a day, does not significantly raise cholesterol levels.
We can’t know to which research Leslie is referring to, because there are no sources cited. However, the studies which depict the results he’s describing are well known. It’s a series of studies with funding by the Egg Board, in which the study was designed with a particular result in mind. For example, in one study, they chose to only measure “fasting cholesterol levels”, at least 7 hours after a meal, because if you wait that long after an egg-laden meal, cholesterol levels return to normal12. In another study, the industry selected people for their trials who started with a total cholesterol of 244, and then tested swapping out sausage and cheese for an egg; unsurprisingly they found that eating eggs instead of Sausage McMuffin did not raise cholesterol any higher than the unhealthy level it already was13. The list goes on14. To be clear, the balance of evidence shows that dietary cholesterol and blood cholesterol are in fact correlated19 20:
If we actually care about the science here (and we should, because our lives are at stake!), then it makes no sense to ignore the significant impact industry-funded studies have had on this debate. Yet this point is oddly overlooked in Mr Leslie’s narrative.
Perhaps the main takeaway from this article is that we should be skeptical of sensationalist nutritional journalism.