The new dietary paradigm: fats

Fats in the diet are a complex issue, still little understood, that has been studied and debated for many years. However, in the last 50 years, it has been considered reasonable to recommend moderate consumption of fats, reducing the most saturated ones and increasing the polyunsaturated ones, and avoiding cholesterol. It has also been stressed that carbohydrate consumption is healthy. Some experts believe that these recommendations hide the epidemic of obesity and metabolic syndrome suffered by a large part of humanity that does not go hungry. Hand in hand with these indications and fleeing from orthodoxy, new dietary advice totally opposed to the current ones has already been proposed. In this entry, we echo these developments.

A widely accepted medical understanding is that obesity is a risk factor for cardiovascular disease, kidney disease, diabetes, some cancers, and musculoskeletal conditions. One of the measures of the degree of obesity is the body mass index (BMI). In order to maintain a healthy BMI, dietary recommendations have been based, until now and in general, on drastically reducing the saturated fats present, for example, in butter, tallow, milk, and red meat, and also the cholesterol they contain, for example, eggs and chicken and beef. At the same time, we have been encouraged to increase the consumption of polyunsaturated fats present in, for example, olive, soybean, sunflower, and corn oils and carbohydrates contained, for example, in rice, pasta, and bread. Even until very recently, the consumption of refined sugars was not a controversial issue as it is now. These recommendations have been followed with more or less adherence in different countries but with more intensity after the introduction of dietary guidelines in the USA in 1977 and in the UK in 1983. The most prominent result, especially in these two countries, is that it has increased the consumption of industrialized food with low-fat content, refined carbohydrates, and polyunsaturated vegetable oils. It is said, for example, that in the USA between the years 1961-2011, 90% of the increase in calories consumed by the population came from carbohydrates and polyunsaturated oils. This is not surprising as many of these guidelines in the UK, USA, and Australia advise that your dinner plates should contain about a third of starchy foods.

Contrary to the objectives for which these dietary guidelines were introduced, the epidemiological studies that evaluate the evolution of obesity in different populations are consistent and forceful in pointing out that obesity has been increasing. The latest and largest of the studies carried out so far was published in early April this year in The Lancet. The article analyzes the results (meta-analyses) of 1,698 previous epidemiological studies conducted between 1975 and 2014 involving more than 19 million people from 186 countries. The conclusions can be summed up simply by saying that in the course of the last 40 years we have gone from a world in which the thin population doubled that of the obese to another world in which there are more obese than thin. In figures, since 1975, the proportion of obese people, corrected for age, has tripled in men and doubled in women. Currently, 2.3% of men and 5% of women have severe obesity (BMI greater than or equal to 35 kg/m2). If the same trend continues, by 2025 a fifth of the population will be obese with more than 6% of men and 9% of women severely obese. The article also points out that this applies to the more or less affluent population and that being underweight remains a public health problem in the poorest countries, especially in South Asia.

In May, a little over a month after this publication, the National Obesity Forum (NOF), which is an organization that brings together British health professionals dedicated to obesity control, made headlines after the publication of the report: Eat fat, cut the carbs and avoid snacking to reverse obesity and type 2 diabetes. In this report, in the form of a decalogue, it is advised to abandon the control of calories, carbohydrates, and low-fat foods and consume fats. This brief report refers to a more extensive one (Healthy eating guidelines & weight loss advice for the United Kingdom) that contains specific dietary recommendations prepared by the Public Health Collaboration (PHC). This is a non-profit organization that publishes quarterly reports on health issues that help improve the quality of life of the British.

The report has made headlines, for example, in The Guardian (Official advice on a low-fat diet and cholesterol is wrong, says health charity) and The Telegraph (Eat fat to get thin: Official diet advice is "disastrous" for obesity fight, a new report warns). Also, New Scientist in its issue of June 11 dedicates the cover, the editorial, and a report to him. In our latitudes, the episode has gone unnoticed except for some blogs or specialized pages such as El Mundo (Eating fat, essential to losing it). In any case, the document has been heavily criticized by the traditional scientific community that insists that the consumption of saturated fats is not optimal for cardiovascular health. Also, the Association of UK Dietitians has disassociated itself from the NOF recommendations, and one of the government bodies responsible for health, Public Health England has described the report as irresponsible and misleading.

All this hype has come after one of the main promoters of this new dietary paradigm, Dr. David Unwin, a Southport GP, received one of the National Health Service's awards for innovator of the year. This award has been given, in part, because Dr. Unwin's diabetic patients following high-fat, high-protein diets spent an average of 70 percent less on medicine than patients following more orthodox regimens.

The first dietary advice that diabetics receive, once diagnosed, is to reduce weight through exercise and eat less fat and more fiber including bread and cereals and also more fruits and vegetables. However, like many healthy people who want to lose weight, this diet does not quite work and after a year of diagnosis, they need oral medication to control glucose levels. Dr. Unwin says that his story began with one of his rebellious diabetic patients who decided on his behalf to go on a low-carb diet. When she responded to Dr. Unwin's call for skipping routine check-ups, he was surprised to find that the patient was no longer diabetic. It was this clue that led him to the risky decision to offer other diabetic patients weekly meetings where they were invited to follow a new regimen. It involved cutting back on more starchy foods (e.g. potatoes) and eating more low-starchy vegetables and less sweet fruits like raspberries and blueberries. Instead of carbohydrates, they were advised to turn to meat, fish, whole milk products, eggs, and nuts. The fact is that patients lost weight and improved glucose control, blood pressure, and cholesterol. Dr. Unwin published the results with the first 19 patients in 2014 and since then other studies carried out in the USA have corroborated these results. One of them involved 34 obese patients with type 2 diabetes. Among them, those who followed a low-carb, high-fat diet with no obligation to count calories ended up with better blood profiles than those who followed the more orthodox diet. Many of these patients were able to stop taking at least one of their diabetes medications.

This type of diet is nothing new and it can be said that it is a rediscovery of the Atkins diet that became famous in the early 2000s. Contrary to all orthodoxy, studies with this diet have shown its effectiveness. In one of 156 women who underwent either the Atkins diet or a low-fat diet, it was observed that after one year the participants on the Atkins diet had lost weight and had better blood pressure and cholesterol than those on the Atkins diet. of the low-fat diet. These results were replicated in another trial that lasted two years.

The idea that dietary fat should be avoided to levels that have become in some places like the UK as low as 1% of total food intake (e.g. see Public Health England "Eat well guide" recommendation earlier this year in attached diagram) comes a long way. Fats are considered the number one enemy against obesity because weight for weight they produce twice as many calories as carbohydrates and proteins. Also, at the beginning of the last century, it was observed that the arterial plaques that cause heart attacks have a high cholesterol content. This observation was followed by several studies that concluded that heart attacks were more frequent in countries where the population consumed fats, especially saturated fats from meat and milk. From this initial relationship between saturated fats and cholesterol comes the bad press that saturated fats receive. In fact, the classification of fats between "good" and "bad" is a very relative issue in light of new evidence.

The benefits of unsaturated fats that we consider heart-healthy are due to their content in omega-3 derivatives that have anti-inflammatory effects, however, their content is highly variable from one fat to another, that is, not all unsaturated oils are equally healthy. It also happens that when we heat many of these vegetable oils, they produce toxic aldehyde-type compounds that have been linked to heart disease, cancer, and dementia. So it is pertinent to ask if it is healthier to fry in sunflower oil or in butter. On the other hand, beliefs related to cholesterol are also shaking. Until now it has been believed that a high concentration of LDL cholesterol (Low-Density Lipoprotein) can cause an increase in arterial plaques. Small LDL particles have recently been shown to induce more plaque formation than larger ones. It has also been seen that the larger LDL particles are produced by the consumption of saturated fats and the smaller ones by the consumption of refined carbohydrates. These data and a good number of recent publications confirm the fact that the influence of dietary fats on human health is still a largely unknown factor. Thus, for example, an analysis (meta-analysis) of a series of studies concludes that diets low in saturated fat are not associated with a lower incidence of heart and brain infarction. On the other hand, randomized clinical trials have led to conflicting evidence, so while some show health benefits from reducing saturated fat intake, others indicate the opposite or no improvement.

All this new evidence is logical that leads us all to scratch our heads and ask ourselves what we should eat. One thing everyone agrees on is that refined sugars are harmful. Regarding the rest of the foods, it is difficult to advise because if one limits the consumption of fats and carbohydrates, one is left with few alternatives. It seems that a good option would be to limit saturated fats, added sugars, and refined carbohydrates and stick to a Mediterranean diet (but high in oil), that is, based on legumes and whole grains, fish, fruit, vegetables, nuts, and olive oil. In our latitudes, it is something that we are used to and that a recent very extensive study, called PREDIMED, has confirmed. We are in luck because the results of the study indicate that, compared to a low-fat diet, a Mediterranean diet supplemented with olive oil or nuts has been shown to reduce heart attacks by a third when followed for a period of five years.

Regarding Dr. Unwin and his diet, it is worth saying that he has published it on an open web page that since its launch last November has collected more than 110,000 subscribers. Of these, some 80,000 have followed the diet for 10 weeks and, in turn, some 2,500 have responded to a survey after 6 months of following the diet. The result of the survey is that the number of patients who initially took antidiabetic drugs, 70% of the total, was reduced to 60% thanks to the diet. In view of this, Unwin has declared that this is a good example of what can be achieved in medicine without too much intervention from health professionals and how the Internet can democratize medicine. These are still some interesting considerations that could be the subject of another entry in this blog.