Intermittent fasting is an eating strategy that involves alternating between periods of eating and fasting. There are several related approaches, including the 16/8 method, in which you fast for 16 hours and eat for 8 hours, or the alternate day method, varying between days of regular eating and fasting.

This practice has become popular due to benefits such as weight loss. “Many studies have been carried out comparing intermittent fasting and weight loss. And, yes, fasting can promote weight loss, as, in addition to causing a restriction or deficit in daily calories, it will contribute to reducing insulin resistance”, explains Dr. Victor Lamônica, otorhinolaryngologist and postgraduate in Integrative, Orthomolecular Medicine and Sports Medicine.

Impacts of Intermittent Fasting on the Brain and Gut

A Chinese study published in the scientific journal Frontiers in Cellular and Infection Microbiologycalled “Dynamical alterations of brain function and gut microbiome in weight loss“, showed that the I blinkedand contributes to weight loss in people with obesity. Furthermore, the research also identified which brain regions and gut bacterial species also respond to this diet and revealed a dynamic correlation between the brain and gut microbiota.

“The changes observed prove the connection in the gut-brain axis, in which it is still not known for sure who influences who, but the changes in brain activity – detected through functional magnetic resonance imaging – occurred in regions that act in the regulation of appetite and addiction, which occur in the cerebral region of the inferior frontal orbital gyrus”, explains Dr. Fernando Gomes, neurosurgeon, neuroscientist and full professor at the Faculty of Medicine of the University of São Paulo.

Study scientists believe that the gut microbiome communicates with the brain in a complex and bidirectional way, as they observed that the microbiome produces neurotransmitters and neurotoxins that access the brain through nerves and blood circulation.

“This proves to us that intermittent fasting, in addition to helping with weight loss, can help the brain work more in favor of food control and, thus, avoid binges on excess food that lead to obesity”, highlights the doctor.

Intermittent fasting helps reduce obesity

According to the Chinese study, intermittent fasting helps reduce obesity and improves clinical parameters related to this health condition, such as blood pressure, total cholesterol and glucose. In the research, 25 obese volunteers were analyzed for 62 days. Everyone followed the intermittent fasting diet and lost, on average, around 7 kg or almost 8% of their body weight.

According to Dr. Victor Lamônica, when insulin is low, due to fasting, the body uses fat as a source of energy. This results in a reduction in the percentage of total fat in the body. “However, not everything is rosy, because when compared intermittent fasting in the weight loss process versus low-calorie diets with physical activity, the results were very similar, with no superiority of one method over another”, explains the doctor.

Relationship between intermittent fasting and eating behavior

The results of the Chinese study also showed that intermittent fasting reduces the activity of brain regions related to eating behaviorthus contributing to the success of weight loss and maintenance.

However, it is important to highlight that intermittent fasting contributes to weight loss when it is well guided and monitored by a doctor and/or nutritionist. As explained by nutritionist Dr. Marcella Garcez, director of the Brazilian Association of Nutrology, this is a weight loss method that is, in most cases, quick and safe for people who have a metabolic profile that is adaptable to fasting.

Benefits for the intestine

The study also identified an increase in intestinal microbial richness and diversity in obese individuals who fasted intermittently. According to Dr. Fernando Gomes, this happens because the dietary pattern interferes with the amount of bacteria in the intestinal flora.

According to him, the digestive system works as if it were a separate “brain”. “It is sensitive to drastic changes in dietary patterns, reflecting the characteristics of the bacteria that naturally live inside us”, he adds.

Challenges of this type of diet

Despite the benefits for health and weight lossthis type of diet also has not so favorable points. When not carried out correctly and without the guidance of a doctor and/or nutritionist, intermittent fasting can put your health at risk.

“The risks increase greatly when intermittent fasting is done without supervision, as people go for long periods without eating and, during periods when they eat, they do so inappropriately”, warns Dr. Marcella Garcez.

According to her, without due care, fasting can cause malnutrition, as well as dehydration, hypoglycemia, muscle weakness and difficulty concentrating. Furthermore, it can “increase the tendency to eating disorders such as binge eating, bulimia and anorexia”.