Intermittent fasting leads to significant changes in both the brain and the gut, a new study on obese individuals has found.
Key findings: The study, published in the journal Frontiers in Cellular and Infection Microbiology, saw participants experience an average weight loss of 7.6 kilograms (16.76 pounds) — 7.8% of their body weight — after an intermittent fasting period of 62 days. Researchers noted changes in the composition of gut bacteria and activity of brain regions linked with appetite regulation and addiction.
The bacteria E. coli, Coprococcus comes and Eubacterium hallii, for example, were negatively associated with activity in the left orbital inferior frontal gyrus, which is involved in executive functions, including the will to lose weight. On the other hand, Parabacteroides distasonis and Flavonifractor plautii were positively associated with activity in areas tied to attention, emotion, learning and motor inhibition.
How the study was conducted: Twenty-five obese volunteers from China participated in an intermittent energy restriction (IER) program for 62 days. They first went through a 32-day “high-controlled” fasting phase with personalized diets of gradually decreasing calories, followed by a 30-day “low-controlled fasting phase” with recommended food intake.
Researchers used metagenomics on stool samples, blood measurements and functional magnetic resonance imaging (fMRI) to analyze changes in the gut microbiome, brain activity and other parameters.
What the researchers are saying: The study’s authors highlighted the two-directional relationship between brain activity and the gut microbiome. Changes in either could be caused by changes in the other.
“The microbiome produces neurotransmitters and neurotoxins which access the brain through nerves and the blood circulation. In return the brain controls eating behavior, while nutrients from our diet change the composition of the gut microbiome,” co-author Dr Xiaoning Wang from the Institute of Geriatrics of the PLA General Hospital in Beijing said in a news release.
The next step, they said, is to determine precisely how the brain and gut microbiome communicate in obese people, including during weight loss. “What specific gut microbiome and brain regions are critical for successful weight loss and maintaining a healthy weight?” said Liming Wang from the Health Management Institute of the PLA General Hospital.
The big picture: Obesity affects more than a billion people worldwide, according to latest WHO figures. These include 650 million adults, 340 million adolescents and 39 million children — and numbers are only increasing.
By understanding the interplay between the brain and the gut, new approaches could be developed to prevent and combat obesity.