The idea that intermittent fasting may help in the fight against unwanted flab is nothing new, but pioneering studies appear to show that timed energy restriction is boosting brain function while making positive changes to the gut’s microbiome.
New Research Suggests Fasting May Rewire the Brain
A groundbreaking study in China, conducted in 2023, has been backed up by promising follow-up work ever since, including a 2024 project that showed how fasting and protein pacing doesn’t just help with weight loss, but also improves the presence of positive gut bacteria. The theory is that fasting doesn’t just torch fat, it also tweaks your body’s ability to handle cravings, even going so far as to reconfigure the brain.
“The gut microbiome is thought to communicate with the brain in a complex, two-directional way,” explained Dr. Xiaoning Wang from the Institute of Geriatrics of the PLA General Hospital, who served as a coauthor on the 2023 study. “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,”
This is important, because some of the changes in eating behaviour experienced as a result of intermittent fasting include the curbing of cravings and more acute self-control as relates to consuming too many calories. Of course, with more than one billion people living with obesity around the globe, a better understanding of how intermittent fasting could help in the battle against the bulge is of major concern.
How Intermittent Fasting Changes the Gut Microbiome
In the original study, a small sample of participants were put on a 32-day fasting phase, gradually restricting their calorie intake until it reached 25% of their energy requirements. This was followed by a 30 day-phase of 500 calories per day for women, and 600 calories for men. By the end of the trial, the subjects had lost around 7.8% of their original body weight, experiencing reduced body fat and waist measurements. But that wasn’t all. Blood pressure levels improved, as did cholesterol and liver enzymes. Using magnetic imaging, the scientists also showed that brain regions associated with appetite, emotion, and reward were rewired.
“A healthy, balanced gut microbiome is critical for energy homeostasis and maintaining normal weight,” said coauthor Dr. Yongli Li. “In contrast, an abnormal gut microbiome can change our eating behavior by affecting certain brain area involved in addiction.”
The Link Between Brain Function and Fat Loss
The changes in brain activity appear to show that intermittent fasting doesn’t just help to burn fat when on a calorie deficit. It could also help us to better control our decisions around the food choices that we make. The 2023 study and follow up reviews have shown that the existence or lack of certain bacteria in the gut can directly relate to the workings of the brain. For example, the presence of Flavonifractor plautii was linked with greater attention levels, emotional regulation, and learning capacity.
Since one of the biggest hurdles in the way of fat loss is the issue of willpower, the idea that intermittent fasting could put us in a better position to make positive choices, without the need for medication, is a welcome one. “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,” explained Dr. Liming Wang. “What specific gut microbiome and brain regions are critical for successful weight loss and maintaining a healthy weight?” Important work continues, to determine the best type of fasting, protein, and calorie consumption for delivering the best results in this exciting area of study.