In 1980, health authorities in the US and the UK issued food guidelines that urged people to eat less fat, less protein, less cholesterol, and more grains and other carbohydrate-rich foods.
People in general (including me) followed that advice, even though in hindsight it has become clear that there was absolutely no evidence that it would work. If you’ve been paying attention, 1980 was about the year that the problem of obesity became an epidemic in the US and in Great Britain. Proponents of a low-carb, higher-protein, low-sugar diet like John Yudkin or Robert Atkins were called all sorts of names by powerful figures in the American and British health establishments, in particular by Ancel Keys and his many acolytes. Yudkin in particular had is reputation besmirched, and Atkins was called a fraud.
Gary Taubes, Nina Teicholz, and Robert Lustig are some of the researchers and writers who have recently pointed out that the familiar low-fat hypothesis has no evidence whatsoever backing it up, and that there is lots of evidence contradicting it.
A few paragraphs from a recent article on this in the Guardian, which I urge you to read in its entirety:
Only in the last few years has it become acceptable to study the effects of Atkins-type diets. In 2014, in a trial funded by the US National Institutes of Health, 150 men and women were assigned a diet for one year which limited either the amount of fat or carbs they could eat, but not the calories. By the end of the year, the people on the low carbohydrate, high fat diet had lost about 8 lb more on average than the low-fat group. They were also more likely to lose weight from fat tissue; the low-fat group lost some weight too, but it came from the muscles. The NIH study is the latest of more than 50 similar studies, which together suggest that low-carbohydrate diets are better than low-fat diets for achieving weight loss and controlling type 2 diabetes. As a body of evidence, it is far from conclusive, but it is as consistent as any in the literature.
In 2008, researchers from Oxford University undertook a Europe-wide study of the causes of heart disease. Its data shows an inverse correlation between saturated fat and heart disease, across the continent. France, the country with the highest intake of saturated fat, has the lowest rate of heart disease; Ukraine, the country with the lowest intake of saturated fat, has the highest. When the British obesity researcher Zoë Harcombe performed an analysis of the data on cholesterol levels for 192 countries around the world, she found that lower cholesterol correlated with higher rates of death from heart disease.
In the last 10 years, a theory that had somehow held up unsupported for nearly half a century has been rejected by several comprehensive evidence reviews, even as it staggers on, zombie-like, in our dietary guidelines and medical advice.
The UN’s Food and Agriculture Organisation, in a 2008 analysis of all studies of the low-fat diet, found “no probable or convincing evidence” that a high level of dietary fat causes heart disease or cancer. Another landmark review, published in 2010, in the American Society for Nutrition, and authored by, among others, Ronald Krauss, a highly respected researcher and physician at the University of California, stated “there is no significant evidence for concluding that dietary saturated fat is associated with an increased risk of CHD or CVD [coronary heart disease and cardiovascular disease]”.
Many nutritionists refused to accept these conclusions. The journal that published Krauss’s review, wary of outrage among its readers, prefaced it with a rebuttal by a former right-hand man of Ancel Keys, which implied that since Krauss’s findings contradicted every national and international dietary recommendation, they must be flawed. The circular logic is symptomatic of a field with an unusually high propensity for ignoring evidence that does not fit its conventional wisdom.