And why don’t you try intermittent fasting? I’m doing great ”. The wonders of intermittent fasting have crept into conversations in the elevator, gym, or mini parent meetings outside the school.
As if it were a seedy telemarketing wedge in an insomniac dawn, the first-person testimonies continue to seem valid arguments, when they are still pure anecdotes without scientific or statistical value.
But Paco is hunky, “knows a lot” about nutrition and follows him. The celebrities who two days ago owed their sculpted body to detox shakes now confess that their secret is intermittent fasting . It seems like irrefutable proof that this pattern works, no matter where you come from or where you want to go.
If you are overweight, you have to try it; if you want to improve your body composition, it is the safe choice. If you want to improve your performance at work -because of course, the zillions of hours you put in a day are not enough-, it already takes time to sign up.
As you already have your football mates and Google to talk to you about the wonders of intermittent fasting -the search engine will offer you more than half a million results in Spanish- and you are one tris from trying it on your own meats, let’s see if you can get those effects spectacular following it on your own. Or if, on the contrary, doing it to your ball has a less attractive reverse.
There is no solid evidence -for now- of those thousands of benefits. In 2018, my partner Juan Revenga wondered if this strategy was appropriate for losing weight and improving health: based on the research that had been published up to that point, his main conclusion was that knowledge on the subject was limited.
Yes, it could potentially have some positive effects – not without risks – but we did not have enough data to bet on it firmly, much less to recommend it to anyone.
The matter is of interest and has continued to be studied intensively. A couple of years give to publish many studies; and revisions of the same to try to obtain a deeper knowledge and a vision closer to reality. But, to general disappointment, it is usually not enough to draw unequivocal conclusions on complex matters. We are in that case.
Intermittent fasting has been proposed as a strategy to help control diabetes ( 1 , 2 , 3 , 4 , 5 ), improve parameters related to cardiovascular health and metabolic diseases ( 1 , 2 , 3 , 4 , 5 ) or increase athletic performance ( 1 ).
Most studies are short-term and only measure indicators – such as blood pressure – but do not assess whether this is reflected in ultimately less cardiovascular disease or diabetes. The results are heterogeneous and inconclusive.
It can happen, because it is not for everyone. The problem is that we are not sure who it can harm because, as with the research on its benefits, there are still not enough studies on its potential risks.
There are cases in which it is clearly contraindicated – at least with what we know so far – and you can already bang your head against the ground, which in no way am I going to tell you that it is a good idea.
Forget experimenting with intermittent fasting if you are pregnant, since the possible risks to the fetus are unknown and the risk / benefit balance does not compensate. The same as if you breastfeed, or are immunosuppressed: from proposing it to small children, we don’t even talk.
In other circumstances, the recommendation points to the same, but it is not as strong. You may have diabetes (type 1 or 2) and have heard wonders about the effects of intermittent fasting on your disease. Entities like the Harvard School of Public Health directly advise against it, and the reality is that there are much safer dietary approaches as recently discussed at JAMA .
But sometimes we are like prey dogs and when an idea gets into our heads we don’t let go of it even under torture, so if you suffer from diabetes and still want to try it, it is absolutely essential that there is a follow-up by the doctor to adjust medication to avoid hypoglycemia and hyperglycemia , and the dietitian-nutritionist to adjust the diet (as explained in Clinical Management of Intermittent Fasting in Patients with Diabetes Mellitus ).
I also tell you that you already want to complicate your life more when, as the 2018 Clinical Practice Guidelines Nutrition Therapy Diabetes Canada explain , the evidence of its effectiveness is limited.
There are also conditions in which, in the absence of unequivocal knowledge , we can reasonably intuit that it is prudent not to follow it. Intermittent fasting consists of a cycle of imposed-intake restriction, which has aroused reluctance about its use in people who are susceptible to eating disorders (eating disorders) (it is inevitable to find certain parallels with the guidelines that incorporate cheat meals or cheat days ).
Although some research finds positive results on eating behavior or on body image ( 1 , 2 ), there are indications that spending many hours without eating can increase the risk of having an episode of overeating or binge eating ( 1 , 2 ) and increase thoughts related to food and fear of losing control ( 1 ).
A person who is suffering from an ED (or has a predisposition) does not have to tell their circumstances to the first one who happens – what’s more, it is that they may not even identify them themselves – that is why it is crucial that the dietary-nutritional advice Give a professional after a detailed evaluation, and not your cousin Lola or a lifestyle influencer. And having safe dietary alternatives, it does not seem like a good idea to recommend this guideline to people at risk.