Appetite control: Intermittent fasting alters gut-brain communication 

A new study published by Frontiers shows that intermittent energy restriction (IER) diets alter communication between the gut and the brain, suggesting a complex interaction between our diet, gut health, and brain function. 

The research highlights the potential of tailored dietary interventions in managing obesity and its related health risks.

Study significance 

The study is particularly relevant given that over a billion people globally struggle with obesity, a condition linked to numerous health risks including cardiovascular diseases, diabetes, and certain cancers. 

Despite the high prevalence of obesity, effective, long-term weight loss remains challenging due to the intricate interplay of gut physiology, hormones, and brain function.

“Here we show that an IER diet changes the human brain-gut-microbiome axis. The observed changes in the gut microbiome and in the activity in addition-related brain regions during and after weight loss are highly dynamic and coupled over time,” said study co-author Dr. Qiang Zeng, a researcher at the Health Management Institute of the PLA General Hospital in Beijing.

How the research was conducted 

The study involved a thorough investigation of 25 obese participants, both women and men, from China. These individuals, averaging 27 years of age with BMIs ranging from 28 to 45, were asked to follow a strict IER diet. 

The researchers used a range of techniques including metagenomics of stool samples, blood measurements, and functional magnetic resonance imaging (fMRI) to track changes in the gut microbiome, physiological parameters, serum composition, and brain activity.

“A healthy, balanced gut microbiome is critical for energy homeostasis and maintaining normal weight. In contrast, an abnormal gut microbiome can change our eating behavior by affecting certain brain area involved in addiction,” explained study co-author Dr. Yongli Li from the Department of Health Management of Henan Provincial People’s Hospital in Henan, China.

The study was conducted in two phases: a 32-day high-controlled fasting phase with stepwise reduced calorie intake, and a subsequent 30-day low-controlled fasting phase with specific dietary recommendations. 

Critical insights 

The impact of this diet was profound: participants lost an average of 16.7 pounds, showing reductions in body fat, waist circumference, blood pressure, and serum levels of various markers like fasting plasma glucose and cholesterol. This indicates the potential of IER diets in mitigating obesity-related comorbidities such as hypertension, hyperlipidemia, and liver dysfunction.

The experts observed changes in both brain activity and the gut microbiome. They noted alterations in brain regions related to appetite and addiction control, as well as shifts in the abundance of specific gut bacteria like Faecalibacterium prausnitzii, Parabacteroides distasonis, and Bacterokles uniformis. 

Intriguingly, the study found correlations between the abundance of certain gut bacteria and the activity of specific brain regions involved in executive functions and emotional processing.

Study implications 

The findings open new avenues for understanding the complex relationship between weight loss, the brain, and the gut microbiome. However, as Dr. Xiaoning Wang noted, the study is correlational, and the exact causality remains unclear. 

“The gut microbiome is thought to communicate with the brain in a complex, two-directional way. 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,” explained Dr. Wang.

“The next question to be answered is the precise mechanism by which the gut microbiome and the brain communicate in obese people, including during weight loss,” said study co-author Dr. Liming Wang. “What specific gut microbiome and brain regions are critical for successful weight loss and maintaining a healthy weight?”

The study is published in the journal Frontiers in Cellular and Infection Microbiology.

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