Intermittent fasting is all the rage right now. And like all fad diets, there is too much talk about it, both for better and for worse, and even experts – at times – seem to turn into fans, losing their usual objectivity. Recently, for example, there are those who have cited a study published in recent days in the journal Cell Metabolism to demonstrate that intermittent fasting offers no advantages compared to a correct diet. And yet, if you look closely, that’s not exactly the case.
The research in question was carried out by a group of American neurologists and neuroscientists, with two precise objectives: to validate a methodology with which to evaluate the effects of diet on brain health, and on this occasion, to test the effectiveness in this regard of two trendy diets, namely a healthy diet that follows the American government’s Dietary Guidelines for Americans, and an intermittent fasting regime.
To achieve these goals, the researchers first chose a series of biomarkers with which to evaluate the effects of nutrition on brain functioning and health. And then a clinical trial was carried out, in which 40 middle-aged overweight people were divided into two groups, one of which followed a healthy diet compatible with American guidelines, rich in fruit and vegetables, and low in saturated fats, salt , sugar and so on, while the others underwent an intermittent fasting regime following the same healthy diet 5 days a week, and instead restricting the calorie intake to just 480 kilocalories per day in the other two.
The participants followed the diet for 8 weeks, and at the end the researchers evaluated the brain health biomarkers they selected to verify the effects of the two dietary regimes. Well, what did they find? In terms of brain health, it has emerged that both diets are useful for reducing neuronal insulin resistance and the rate of brain aging. Both produced improvements in memory and executive function (the set of cognitive processes such as language, memory, perception and motor control, which contribute to planning and carrying out goal-oriented behaviors), but those linked to intermittent fasting were greater . Neither diet produced improvements in biomarkers linked to Alzheimer’s risk. And to top it off, intermittent fasting produced much greater reductions in body mass index and weight loss (about double) than what was seen with the healthy diet alone.
How should these data be interpreted? Healthy diet and intermittent fasting in the study were equally beneficial for brain well-being. Intermittent fasting has been found to be more effective in improving some cognitive functions, and much more useful for losing weight. That’s it: The study wasn’t designed to fully evaluate weight loss, its duration, and the metabolic effects or cardiovascular benefits of the two diets.
Saying that intermittent fasting has not demonstrated advantages compared to a correct diet (as some Italian experts have done) is therefore incorrect, unless we are referring solely to the effects it has on the brain (and even in that case, as we have seen , that wouldn’t be entirely true). This is difficult to take for granted, given that usually the benefits cited when talking about intermittent fasting are those related to weight loss and cardiometabolic health. How does the misunderstanding arise? The first to tweet about it was Eric Topol, a well-known American cardiologist (founder of the Scripps Research Translational Institute) who has become a point of reference in the social communication of science during the pandemic. An imprecise tweet from him probably turned, inadvertently, into a source of fake news.