Intermittent energy restriction tied to gut, brain changes
In people with obesity, weight loss by intermittent energy restriction (IER) has multiple, dynamic effects on the brain-gut-microbiome (BGM) axis, including reduced activity in brain regions affecting eating behavior and increased microbial diversity in the gut, over the short term, new research suggested.
METHODOLOGY:Researchers studied 25 individuals with obesity in China who successfully lost weight during a three-phase IER intervention. In the first phase, participants were on a normal diet without restriction for 4 days. In the second, they were on a tightly controlled diet of clinically formulated IER meals every other day that decreased stepwise in caloric value to one quarter of their basic energy intake over 32 days. The last phase was a 30-day low-controlled fasting period.
Blood and stool samples were collected at baseline, at the midpoint and endpoint of the tightly controlled fasting phase, and at the endpoint of the low-controlled fasting phase.
A functional MRI was used to determine the activity of specific brain regions, and metagenomic sequencing was performed to identify differentially abundant gut microbes and pathways from stool samples.
TAKEAWAY:Patients lost weight (7.6 kg on average) and showed sustained, significant reductions on several measures, including body mass index, body fat, systolic blood pressure, and serum levels of glycosylated hemoglobin during the IER. Diastolic blood pressure, serum levels of fasting plasma glucose, total cholesterol, various lipids, and levels of several key liver enzymes were significantly decreased at at least one timepoint during the IER.
IER reduced the activity of obesity-related brain regions (ie, the inferior frontal orbital gyrus in the cognitive control circuit, the putamen in the emotion and learning circuit, and the anterior cingulate cortex in the sensory circuit) at different timepoints during the intervention. No significant changes were observed in brain activity in the reward circuit.
Gut microbial diversity increased during the tightly controlled fasting phase. The abundance of the probiotic Faecalibacterium prausnitzii, Parabacteroides distasonis, and Bacterokles uniformis was elevated during this phase. The abundance of pathogenic Escherichia coli was reduced across multiple timepoints. A correlation analysis revealed longitudinal correlations between gut bacteria abundance alterations and brain activity changes.
Overall, there was a dynamical alteration of the BGM axis during weight loss using IER, although whether changes in the gut microbiome drive changes in the brain, or vice versa, is still unknown.
IN PRACTICE:"IER induced constant, significant reductions in the activity of eating behavior-related brain regions…[and] significant, dynamic changes in the abundance of some gut bacteria. Importantly, gut microbiota alterations correlated with brain activity changes across different timepoints in IER intervention. These data suggest that the dynamic interplay between the brain and gut microbiota plays an important role in weight loss," the authors wrote.
SOURCE:Jing Zhou, Henan Provincial People's Hospital, Zhengzhou University People's Hospital, Henan University People's Hospital, Zhengzhou, China, led the study, which was published online on December 30, 2023, in Frontiers in Cellular and Infection Microbiology.