The world of diets is made up of fads, more or less effective. Among the trends of recent years, one of the most widespread and discussed is certainly intermittent fasting: the diet that involves losing weight by limiting the number of meals you eat over the course of a day. There are many different versions, but the gist is that by fasting for part of the day, or every other day, you should be able to lose weight and reduce the effects of metabolic, cardiovascular and oncological diseases better, and more easily, than with traditional low-calorie diets. There is no shortage of favorable data, but neither are there any doubts on the part of the scientific community. And new research that is causing a lot of talk these days goes precisely in this direction: intermittent fasting – suggests the study carried out by a team of Chinese and American researchers – would in fact appear to be linked to a greater risk of death from heart disease.
I study
The research in question was presented in recent weeks during a conference of the American Heart Association, but has not yet been published in a scientific journal. And having not yet passed the peer review required in these cases, it should be taken for what it is: a preliminary result, which will need to be further examined by the scientific community in order to be considered reliable.
Having said this, we can look better at what the research says. Its authors used data collected from the National Health and Nutrition Examination Survey, a long-running census that collects information on the diet and health of tens of thousands of American citizens. Analyzing those of 20 thousand people interviewed between 2003 and 2018, the authors of the research evaluated the risk of dying due to heart attack and heart disease for those who rely on intermittent fasting, defined in this case as the consumption of meals over of only 8 hours during the day, comparing it with that of those who spread their meals over 12 or 16 hours of the day. For the former, the percentage of deaths from cardiac causes was 7.5%, while in the other two groups it was 3.6%. In these terms, therefore, intermittent fasting would seem to increase the risk of dying due to a heart problem by 91%.
The doubts
Many experts have greeted the new research with wariness. First of all, as we were saying, these are results that have not yet been verified by the scientific community, and it is therefore impossible to establish whether everything was done correctly. Taking into account, for example, the many factors that can influence cardiovascular risk (such as obesity, sedentary lifestyle, cigarette smoking, age, and so on). As well as those that can influence the diet: it is possible, for example, that those who consumed meals in the space of just 8 hours did so due to a hectic job, a lack of appetite linked to health problems or taking medications, or because perhaps he had chosen intermittent fasting precisely to remedy the effects of some other pathology, all variables that could drastically change the interpretation of the research results.
Net of these considerations, it must be said that in the past some studies had already found a link between intermittent fasting and health risks. Like a research we told you about last year, carried out by researchers from the University of Tennessee, the University of Iowa and the University of Wuhan, which showed a greater risk of premature death in people who skip at least one meal throughout the day. Some research carried out on patients with heart failure and diabetes is also of a similar nature, for whom concentrating meals in a short time window throughout the day seems linked to worse health outcomes and greater mortality.
So what to do?
Summing up, in this case, is not easy. Historically, research on intermittent fasting has been complicated by many factors, one being the variety of approaches that exist: diets that involve consuming meals only in a limited portion of the day, others that recommend fasting (or drastically limiting calories) only one or more days of the week, others like the (relatively) famous fasting mimicking diet, which prescribe a precise low-calorie food plan to be followed one week a month.
In recent years, however, several randomized clinical studies (the most reliable on a scientific level) have been carried out on the effects of intermittent fasting, and the results all point in the direction of a benefit in terms of weight loss and improvement of various cardiovascular risk factors (such as blood pressure and cholesterol). The research that indicates potential risks, however, for now is all observational, a type of study that can show correlations between two phenomena but does not allow conclusions to be drawn in terms of causality: it is not enough to see more deaths from cardiac causes among people who practice intermittent fasting, as we were saying, to establish that it is the cause (and not perhaps a consequence) of the problem. How fasting for part of the day might be bad for your health is also unclear. And without this “biological plausibility” no strong conclusions should be drawn from research. If you want to try intermittent fasting, therefore, there is no need to be excessively scared. Remembering that when in doubt, as always, the best thing is to ask your doctor for advice.
Bassetti against Viola
The research did not escape the attention of the director of Infectious Diseases at San Matteo in Genoa, Matteo Bassetti, who took the opportunity to launch a jab at the biologist and professor at the University of Padua Antonella Viola with whom he had also had a disagreement related to alcohol consumption .
The #intermittentfasting intermittent, which is so fashionable in Italy also because it is promoted by self-proclaimed nutrition experts, increases the risk of cardiovascular mortality. The observational analysis, just presented at an American cardiology congress, of over…
— Matteo Bassetti (@ProfMBassetti) March 26, 2024