From the stomach to the brain, intermittent fasting affects our body in unexpected ways

Intermittent fasting has become popular among those who want to lose weight or keep their calorie intake under control. Not without risks and controversiesthis practice has grown in popularity spurred by the positive results with which it has been associated. For better or worse, we continue to study what its impacts are on our body.

Fasting and the brain. And one of the latest studies in this field has found a relationship between intermittent fasting (or intermittent calorie restriction) and changes in our brain and gastrointestinal systemOne of the keys to these changes may be in the intestinal microbiome, although the cause-effect relationships are still unclear.

Intermittent fasting. Humans have practiced fasting in various forms for centuries. However, fasting as a way to lose weight has become one of the most widely practiced methods today.

There are various intermittent fasting methodsSome of these methods involve going a set number of hours a day (12 or 16) without consuming anything other than water. Other versions involve going days without eating, either a number of days a week, or on alternate days, or in other ways.

25 participants. The study was conducted with 25 participantswomen who had been diagnosed with obesity. The experiment lasted two months, during which the group followed an intermittent fasting program. The program included alternating between days of a “normal” diet with days in which caloric intake was limited to a greater or lesser extent through fasting.

The team responsible for the study analyzed the changes in the participants’ brains through magnetic resonance imaging scans (fMRI); while changes in the gastrointestinal microbiome were studied through blood and stool samples.

More than losing weight. Intermittent fasting often shows results when it comes to weight loss, and this latest study is no exception: on average, participants lost 7.6 kg of weight during the intervention; and 7.8% of their body mass, also on average.

However, the key to the study is not in the weight loss but in the changes observed in the brain and gastrointestinal system. In the brain, the team observed changes in brain regions conventionally linked to appetite and addictions.

Changes in the microbiota. In the case of the gastrointestinal system, the team observed a change in the composition of its microbiota. They observed, for example, increases in the relative presence of bacteria Faecalibacterium prausnitzii, Parabacteroides distasonisand Bacterokles uniformis; along with a reduction in the presence of Escherichia coli.

The team also linked these bacterial changes to certain brain areas. For example, the abundance of bacteria E. coli, Coprococcus comes and Eubacterium hallii was associated with the activity of the left inferior orbital frontal gyrus, while bacteria such as P. distasonis and Flavonifera plautii were associated with activity in brain regions that we link to motor functions, emotions, and learning.

The details of the study were published in an article in the magazine Frontiers in Cellular and Infection Microbiology.

Cause and effect. The correlation between these changes seems clear, but not the cause-effect relationship. That is, whether it is the changes in the brain that generate changes in the microbiota or whether it is the changes in the gastrointestinal system that somehow generate alterations in the brain of the participants.

“A healthy and balanced gut microbiome is critical for homeostasis and maintaining a normal weight. In contrast, an abnormal microbiome can change our eating behavior, affecting the area of ​​the brain involved in addiction,” explained in a press release Yongli Li, co-author of the study.

Elucidating the question of causal relationships may be the next step in research. To do so, it will be useful to better understand the mechanisms that communicate between the brain and the gastric system.

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Image | Jane Trang Doan / Cats Coming