Intermittent fasting (intermittent fasting) can not only contribute to weight loss in those who are overweight and obese, but can also influence the intestinal flora and have positive effects in the brain via the gut-brain axis.
A recent study examined the effect of intermittent fasting with alternating days of fasting and days of normal nutrition on weight, intestinal flora and the brain. The results are published in the specialist journal “Frontiers in Cellular and Infection Microbiology”.
Difficulty losing weight
Overweight and obesity bring with them an increased risk of cardiovascular diseases, diabetes and various cancers, which is why those affected are urgently advised to lose weight. However, losing weight and then maintaining a healthy body weight is often difficult.
It is known that complex interactions between body systems such as intestinal physiology, hormones and the brain can work against the desire to lose weight, the team reports.
Intermittent fasting in different forms
Intermittent energy restriction (intermittent fasting) is still considered a promising approach to achieve lasting weight loss. However, different forms of intermittent fasting are practiced.
Some methods limit daily food intake to a certain period of time, others provide for a daily alternation between fasting days and normal nutrition. The researchers used the latter method in the new study.
Effects of daily fasting examined
They tested the effect of this special form of daily intermittent fasting on 25 participants with an average age of 27 years and a body mass index (BMI) between 28 and 45.
After a four-day starting phase with a normal diet, 25 participants went through a 32-day strictly controlled fasting phase in which they fasted every other day. For this purpose, they received individually designed meals from a dietitian, the calorie value of which was gradually reduced to a quarter of their basic energy intake on the fasting days.
This was followed by a 30-day fasting phase in which the participants chose their own diet based on a list of recommended foods. Those who followed the recommendations perfectly consumed 500 calories per day (women) or 600 calories per day (men) on the fasting days.
The team explains that changes in intestinal flora, physiological parameters and serum composition were determined using genomic studies of stool samples, blood tests and functional magnetic resonance imaging (fMRI).
Significant weight loss achieved
At the end of the study period, the participants’ body weight had reduced by an average of 7.6 kg or 7.8 percent and, as expected, the body fat percentage and waist circumference had also decreased, the researchers report.
In addition, blood pressure and serum levels of fasting plasma glucose, total cholesterol, HDL and LDL, as well as the activity of major liver enzymes also decreased, suggesting that intermittent fasting could reduce obesity-related comorbidities such as hypertension, hyperlipidemia and liver dysfunction.
Changes in intestinal flora
In the intestinal flora, there was a strong increase in the bacteria Faecalibacterium prausnitzii, Parabacteroides distasonis and Bacterocles uniformis, while the frequency of Escherichia coli decreased.
According to the researchers, fasting also causes a decrease in activity in brain regions that are involved in regulating appetite and addiction. The experts were also able to determine a connection between intestinal bacteria and brain activity.
Effects on the brain
Further analyzes showed that the abundance of Escherichia coli, Coprococcus comes and Eubacterium hallii was negatively related to the activity of the left orbital inferior frontal gyrus of the brain, the team reports.
This brain region is known to play a key role in executive functions, including our desire to lose weight.
On the other hand, an increased occurrence of Parabacteroides distasonis and Flavonifractor plautii is associated with higher activity in brain regions that are related to attention, motor inhibition, emotions and learning.
These results suggest that changes in the brain and microbiome during and after weight loss are related to each other – either because they are mutually dependent or because an unknown other factor causes both, the researchers conclude.
Further studies required
A healthy, balanced gut flora is crucial for energy homeostasis and maintaining normal weight, while an abnormal gut microbiome can alter eating behavior by affecting certain areas of the brain involved in addiction.
Further studies now need to decipher the exact mechanisms through which the intestinal flora and the brain communicate in obese people, including during weight loss. The question also arises as to which specific factors of the intestinal flora and the brain are crucial for long-term successful weight loss. (fp)