Researchers from China monitored 25 obese patients losing weight during and after intermittent energy restriction (IER) for changes in their gut bacteria and in brain regions for appetite and addiction. They showed that changes in both these compartments of the brain-gut-microbiome axis are tightly coupled in time. These results suggest that these changes could be linked by an as yet unknown mechanism: either changes in the gut microbiome drive changes in the brain or vice versa.

Worldwide, more than one billion people are obese. Obesity is a risk factor for cardiovascular disease, diabetes, and some cancers. But permanently losing weight isn’t easy: complex interactions between body systems such as gut physiology, hormones, and the brain are known to work against it. One method for weight loss is intermittent energy restriction (IER), where days of relative fasting alternate with days of eating normally.

“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 addiction-related brain regions during and after weight loss are highly dynamic and coupled over time,” said last author Dr Qiang Zeng, a researcher at the Health Management Institute of the PLA General Hospital in Beijing. The results are published in Frontiers in Cellular and Infection Microbiology.

The fast track to weight loss

The authors used metagenomics on stool samples, blood measurements, and functional magnetic resonance imaging (fMRI) to study changes in the composition of the gut microbiome, physiological parameters, and serum composition, and brain activity in 25 obese Chinese women and men on an IER diet. Participants were on average 27 years old, with a BMI between 28 and 45.

“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 coauthor Dr Yongli Li from the Department of Health Management of Henan Provincial People’s Hospital in Henan, China.