Intermittent fasting, a cause of cardiovascular risk?
An American study supports that fasting increases the risk of cardiovascular death in the long term. Experts, including Genevans, question these results.
Intermittent fasting is often presented as a vector of benefits. Is this scientifically proven?
Keystone
The image of intermittent fasting has taken a big hit. According to a study presented at the Congress of the American Heart Association – one of the largest societies of cardiologists in the world – this dietary practice will greatly increase the risk of cardiovascular diseases in the long term. In the face of the media frenzy caused by this announcement, nearly thirty international experts in intermittent fasting wrote an open letter to denounce the flaws in these results.
The form of fasting considered by the study is 16/8, or eight hours of food consumption and sixteen hours without food. Chinese researchers used data from an American study based on 20,000 adults aged 48 years, on average, over eight years. They say their results showed that the risk of dying from cardiovascular disease was almost doubled among participants who adopted the 16/8 diet.
“Preliminary Results and Prejudices”
A group of 34 international researchers working on intermittent fasting decided to respond to “this alarmist message of anger”. One of them is Dr. Tinh-Hai Colette, assistant professor of endocrinology, diabetology, nutrition and therapeutic education at the University Hospitals of Geneva (HUG). “The idea is not to hide scientific information, but to moderate the message, because these very surprising results are questionable.”
The doctor first notes that these are preliminary results, “which are not subject to evaluation by peer experts in the field as in practice”.
Then, on the merits: “Certain confounding factors were not sufficiently taken into account when adjusting the results, especially the rate of smokers in the cohort,” maintains the Geneva doctor. However, tobacco is one of the most important causes of cardiovascular mortality.”
ethnic group
A similar observation for the ethnicity measure, “while it is established that the rate of hypertension is higher among Black Americans than Caucasians, as is the risk of heart attack and stroke”.
It is also not clear whether the participants were following regular intermittent fasting with the same meal schedule every day “when the synchronization of eating rhythms with the biological clock plays a central role in many cardiovascular and metabolic diseases.
Finally, he adds, the researchers did not take into account socioeconomic context or diabetes, “although diabetics have a much higher risk of heart attack. So these results should be taken with great caution, especially since there are no other studies that corroborate such results, to the contrary.
“Not a miracle cure”
Intermittent fasting is often presented as a vector of benefits. Is this scientifically proven? “Some studies show benefits, such as slight weight loss, lower blood pressure in some people, sometimes better control of sugar levels,” answers Tinh-Hai Collette. Others, in animal research, have also shown longevity extension.
Although we are far from a miracle cure, it puts things into perspective. “Some work has also shown that this practice may have little or no effect.”
Claire Pijolet, a dietitian and lecturer at the Haute École de santé de Genève, does not widely recommend this practice, “because even if some studies have reported positive effects on metabolism, scientific evidence is lacking, especially in the long term. Additionally, 16/8 fasting is often not consistent with habits, making it difficult to implement this change on a daily basis over time.
Hydrate well
She recalls that intermittent fasting appears in the context of the increasing prevalence of obesity, where diets are abundant. “It appears to be an “innovative” solution, as the focus is on the temporality of food intake, not on the food itself. However, to obtain positive effects, it is not enough to distribute food intake! The quality and quantity of calories consumed during meals are the decisive factors.”
And he added that fasting enthusiasts should take care to stay well hydrated even outside of food intake, and that in terms of metabolic diseases like diabetes, the practice can present certain risks without medical help.
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