Weight loss through slimming significantly alters the microbiome and brain activity

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

“Here we show that an IER diet modifies the human brain-gut-microbiome axis. The changes observed in the gut microbiome and in the activity of brain regions linked to addition during and after weight loss are very dynamic and coupled in time,” said final author Dr. Qiang Zeng, a researcher at the Institute of Health Management at Beijing PLA General Hospital. The study was published in Frontiers of cellular and infectious 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 gut microbiome composition, physiological parameters and serum composition, as well as activity brain in 25 obese Chinese women and men following an IER diet. . Participants were on average 27 years old and had a BMI between 28 and 45.

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

First, participants underwent a 32-day “highly controlled fasting phase” during which they were given personalized meals designed by a dietitian, with the caloric value gradually decreasing to a quarter of their energy intake. basic. They then spent 30 days in a “weakly controlled fasting phase,” during which they were given a list of recommended foods: Participants who fully adhered to this diet would receive 500 calories per day for women and 600 calories per day. day for men.

Synchronous changes in brain activity and the gut microbiome

By the end of the study, their body weight had decreased by an average of 7.6 kg, or 7.8%. As expected, their body fat and waist size decreased.

Likewise, their blood pressure and serum levels of fasting plasma glucose, total cholesterol, HDL and LDL had decreased, as well as the activity of major liver enzymes. These suggest that IER helps reduce obesity-related comorbidities such as hypertension, hyperlipidemia and liver dysfunction.

The authors observed a decrease after IER in the activity of brain regions involved in the regulation of appetite and addiction. Within the intestinal microbiome, the abundance of the bacteria Faecalibacterium prausnitzii, Parabacteroides distasonis and Bacterokles uniformis increased significantly, while that of Escherichia coli decreased.

Further analyzes showed that the abundance of E. coli, Coprococcus come, and Eubacterium hallii bacteria was negatively associated with activity in the brain’s left orbital inferior frontal gyrus, known to play a key role in executive function, including our desire to lose weight. In contrast, the abundance of the bacteria P. distasonis and Flavonifractor plautii was positively correlated with the activity of brain regions associated with attention, motor inhibition, emotion and learning.

Weigh the evidence

These findings suggest that changes in the brain and microbiome during and after weight loss are linked, either because they cause each other or because another unknown factor is causing both. Because the study is correlational, it cannot determine the direction of underlying causality.

“The gut microbiome is thought to communicate with the brain in a complex, bidirectional manner. The microbiome produces neurotransmitters and neurotoxins that access the brain through nerves and the bloodstream. In return, the brain controls eating behavior, while that nutrients in our diet change the composition of the gut microbiome,” said co-author Dr. Xiaoning Wang of the Institute of Geriatrics at PLA General Hospital.

Co-author Dr Liming Wang, also from the Health Management Institute in Beijing, said: “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. The gut microbiome and brain regions are essential for successful weight loss and maintaining a healthy weight? »