Although more research is needed on the health effects of intermittent fasting, the various studies look promising.
Intermittent fasting seems like the latest fad diet. However, it is not used solely for weight loss, but could be considered a nutritional strategy with health benefits. In fact, for weight loss, the diet based on intermittent fasting does not differ much from that achieved with any other calorie restriction protocol.
There are many types of fasting protocol, of different duration (whole days or hours), on alternate days, with different frequency of intakes, etc.
The simplest modality and the easiest to integrate into daily life is the one that consists of skipping breakfast or dinner. With this we could be able to fast for 16 or 18 hours and eat in a balanced way in the so-called “feeding window” of 8 or 6 hours.
However, what use would fasting supposedly improve our health if we later eat badly? Indeed, to take advantage of the benefits of fasting, we must do it for a certain number of hours and eat in a balanced way in the feeding window. Without excesses and avoiding processed food.
In no case is it a compensatory mechanism for a poor diet and should be seen as an adjuvant tool within the framework of a balanced diet.
During the feeding window, the frequency of meals is not particularly relevant, however it is important to eat consistently and avoid “snacking” every so often, as it would not be the most optimal from the point of view of eating habits.
So, during the hours when we can eat, we should eat, for example, two larger meals and a snack. In addition, we must stay well hydrated in the hours in which we fast. This is important because our body uses glycogen stores to produce glucose and this process requires water to take place.
This is why we urinate more and remove a little more electrolytes. These, later, can be replaced by drinking water, infusions etc.
But what health benefits, regardless of whether or not weight loss occurs (which is not always the goal), can fasting entail?
Our ancestors were totally used to enduring periods of fasting. For this reason, our organs respond to it and generate an adaptive cellular response to stress (fasting is still a stressor), which includes various events.
In a study where volunteers fasted for 14 hours for a month, a significant increase was seen in several protein products of tumor suppressor genes and DNA repair.
It has also been seen that it can reduce oxidative stress, responsible for tissue damage. It was shown in a study in which in prediabetic men, after 5 weeks of fasting, the plasma levels of 8-isoprostane, a marker of lipid oxidative stress, decreased.
Likewise, it was observed in the results of another study in which, after 8 weeks of fasting every other day, obese patients with moderate asthma experienced a decrease in inflammation markers (such as TNF-alpha) and stress markers oxidative (8-isoprostane and nitrotyrosine).
These studies provide hope for the use of fasting to prevent or treat arthritis or other autoimmune diseases, which are based on inflammatory factors and oxidative stress.
A boost to autophagy
Another mechanism in which intermittent fasting works is autophagy. Autophagy is a process that eliminates cellular debris that intervenes in aging and in certain diseases. In addition, it stimulates the regeneration of tissues.
In animal models it is widely demonstrated that caloric restriction increases longevity. In humans, populations such as the island of Okinawa, who have a low-calorie diet with unprocessed plant foods and complex carbohydrates, show high longevity.
For its part, a recently published review in the New England Journal of Medicine collected scientific evidence of the effects of intermittent fasting on aging, health, and disease.
This work concluded that this type of fasting seems to have a positive effect on diseases such as obesity, diabetes, cardiovascular diseases, cancer and some neurological diseases.
In this review it is collected that, both in animal and human models, it has been seen that it improves insulin sensitivity, prevents obesity and improves some markers of cardiovascular health, such as LDL (low-density lipoprotein) and HDL levels (high-density lipoproteins).
Another field in which the implications of intermittent fasting for our health are studied is that of cancer. In animals, caloric restriction has been shown to suppress the growth of some tumors. In addition, it increases their sensitivity to chemotherapy and radiotherapy. This happens because it possibly complicates the energy metabolism of cancer cells.
Currently, there are several ongoing clinical studies on the use of intermittent fasting in cancer patients that will allow us to corroborate whether there is a correlation with the results obtained in animal models.
Finally, it is important to note that there are still no specific studies on the possible differences that may exist in the benefits of intermittent fasting between men and women. Recently, at the Open University of Catalonia, a study has just started in postmenopausal women to see if intermittent fasting has effects on genes that intervene in aging and the clinical manifestations of menopause.
Thus, although the results seem promising, longer and more rigorous studies are required that take into account more population groups and even differences between the sexes, to be able to affirm these effects with completeness.