Intermittent fasting

Surely you have heard or read something about “intermittent fasting“.  But what does intermittent fasting really mean?  Does it have any scientific basis?  Is it really proven to help combat diseases like cancer?  I will answer all of these questions in this post.

What is fasting?

Intermittent fasting is based on limiting the intake of food to non-caloric liquids such as water, coffee, herbal teas, or even vegetable and bone broths for a period of between 16 and 72 hours1. Fasting is as old as humanity itself, and our historical ability, or inability, to consistently access food. The industrial revolution provided continuous access to food for a percentage of the world’s population.  In this part of the planet, the so-called first world, obesity is reaching epidemic proportions and is associated with at least 13 types of cancer.  Our unlimited access to food, combined with a lower quality of food and an exponential increase in the consumption of processed foods in the last 50 years, is ironically causing an epidemic of malnutrition2,3.

What does science say about fasting?

Due to historical reasons and scientific ignorance, until a few years ago fasting had remained in the realm of religious traditions and those suffering from starvation.  However, science and medicine have rediscovered a tradition as old as our very existence.

It shouldn’t surprise us that our mothers used to say “if you’re hungry, you’re not that sick,” as our own bodies tell us not to eat when we are sick.  However, it is not uncommon for someone close to you to advise you to eat when you are ill even if you are not hungry — science is showing this advice to be wrong.  Short fasts (16-72h) improve many metabolic factors, can prevent disease, and can even keep us more attentive in our daily tasks1,4.  These effects are due to the fact that in these periods of fasting, mechanisms such as autophagy, one of the recycling and repair systems of the human body, are activated5. We will discuss autophagy in greater depth in future posts.  We know what happens in our cities when the recycling and garbage collection systems don’t function – and exactly the same thing happens in our bodies: they fill up with garbage5.

Beneficio de tomar infusiones

Is it really proven to help combat diseases like cancer?

In addition to being fashionable in media and pop culture, intermittent fasting is also popular in the field of cancer treatment, due to the potential improvement in the effectiveness of chemotherapy and reduction of its side effects6. How much of this potential is real?

The main effect of fasting is a decrease in circulating glucose levels, as well as a decrease in the levels of pro-cancer hormones6,8. During fasting, normal cells pass from a proliferative state to one of maintenance and repair.  In contrast, tumor cells lack this ability to enter this “maintenance shop“.  In this way, by suppressing the source of nutrients and growth factors available to these tumor cells, they become more sensitive to anti-tumor treatments9, 10.

In fact, short-term fasts (48h) have been shown to enhance the effects of chemotherapy and immunotherapy7,1114. The most promising results have been observed in patients with breast or ovarian cancer, where intermittent fasting was shown to decrease chemotherapy-associated toxicity15,16. In another study, in patients with HER2-negative breast cancer undergoing chemotherapy, fasting improved the efficacy of treatment.  Not only that, but in the fasting group it was not necessary to use corticosteroids to alleviate the side effects of chemotherapy17.

In summary, we must have a comprehensive view of serious pathologies in which the risk-benefit balance of the different therapeutic options available can be assessed.  Intermittent fasting is safe in animal models, healthy subjects, and cancer patients, with very promising results in the context of cancer6. Furthermore, the side effects of intermittent fasting in humans are quite mild and transient, including for example headache, dizziness, nausea, weakness, and temporary weight los6.

Therefore, as long as it is prescribed and controlled in a personalized way by a health professional, the benefits of intermittent fasting can far outweigh the possible risks.

If you’re the curious type with a restless mind, you will surely have many questions after reading this post.  If so, write us on our social networks (i.g., Facebook) where we will answer all your questions, along with many that have not yet been asked.  Join the team of restless minds, join Ibions!


Julio Madrigal Matute

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