For years we have been sold that intermittent fasting It was the strategy of the future to lose weight and improve our metabolic health. It is logical: it was something easy to implement, reasonable and very striking. Had everything necessary to become a fashion. And so it was.
It is now, as the first long-term studies come to an end, that we begin to really understand its pros and cons. The most striking, of course, is the one that has to do with hair.
What exactly is intermittent fasting? In general terms, we call ‘intermittent fasting’ a diet that alternates periods without food restrictions with brief periods of fasting. ‘Fasting’, here, is a deliberately elastic term: it can mean eating absolutely nothing or significantly reducing the number of calories consumed.
The idea behind it sounds good.. When we undergo prolonged calorie restriction, the body goes into “savings mode” and that causes weight loss to slow down (or, at least, slow down). Intermittent fasting would attempt to trick the body into not adapting to the new calorie restriction and therefore continuing to “spend” at a normal rate.
And does it work? That’s the bad news. “Research does not consistently show that intermittent fasting is superior to continuous low-calorie diets” when it comes to weight loss, the study tells us. more complete analysis on the subject after reviewing almost fifty studies.
The clinical trials that have been carried out Subsequently, they only insist on the same thing: in general terms, the results are identical to those with the rest of the normal diets. Both in the dropout rate and in the amount of weight achieved or the improvement in health markers.
The choice of another method, ultimately, has more to do with individual philias and phobias than with any type of extra scientific evidence. After all, everyone has a peculiar relationship with food and, consequently, there are some strategies that ‘fit’ us better than others.
In other words, there are people who use it. Yes and the truth is that nothing happens. Little by little, researchers are discovering good things (can help intestinal cells regenerate) and bad things (could promote the formation of precancerous polyps). So, little by little, we are better understanding what it does, what it stops doing and what mechanisms are behind intermittent fasting.
That’s when the surprises begin. Because, for example, a clinical trial carried out with mice has discovered that intermittent fasting slows hair growth. Researchers at Westlake University (in Zhejiang, China) took about 50 mice, shaved them and divided them into three groups with dietary restrictions (fed every 8, 16 or 48 hours) and one without restrictions which is the control group.
After a month, the mice that could eat without problem had recovered their hair. Those who fasted, on the other hand, only partially recovered after 96 days.
As? Because? What is happening here? The first thing is to make it clear that the researchers “They don’t want to scare people away from intermittent fasting.“; but rather highlight “the importance of taking into account that it could have some unwanted effects.”
Taking this into account (and that the study is in mice), the answer is both simple and full of uncertainties: to begin with, hair growth is a process that requires constant and balanced nutrition.
But researchers believe the problem could go further: It is possible that “the body uses fat reserves instead of glucose and this could trigger the release of chemicals that damage hair cells.” However (and this is important) the research is in a very seminal state and there is still much to investigate.
After all, there is no better occasion than this: the occasion they paint her bald.
Image | Seika
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A version of this topic was originally published in February 2025
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