Losing weight by intermittent fasting can ‘drastically change’ the way your brain works – both positively AND negatively

Intermittent fasting, touted by celebrities like Hugh Jackman, Beyoncé and Kourtney Kardashian, can have major effects on your brain, a study suggests.

Scientists at the Health Management Institute in Beijing have found that intermittent fasting can drastically change gut bacteria and brain activity, which can have both positive and negative consequences.

The most popular form of the trendy diet – time-restricted eating – involves people limiting their food intake to eight to 10 hours a day, going without food for 14 to 16 hours.

Another form of the diet involves alternating days of fasting, where you eat very little, with days of normal eating.

Chinese researchers studied the effects of this method of intermittent fasting on overweight and obese participants and found that the regimen led to a decrease in brain activity that plays a role in appetite and addiction, as well as an increase in gut bacteria linked to attention, emotion and learning.

The results could indicate that intermittent fasting can do more for people than just help them lose weight.

Dr. Yongli Li, co-author of the study from Henan Provincial People's Hospital in China, said a healthy gut is essential for maintaining overall balance and improving health in all parts of the body.

Researchers studied 25 overweight and obese participants from China who followed two different intermittent fasting regimens for two months.

Participants were on average 27 years old and had a body mass or index (BMI) ranging from 28 to 45.

To demonstrate how fasting diets affect the body, participants gI have had stool samples, blood samples taken and brain scans.

First, they ate their normal diet for four days so that the researchers could assess their average daily energy intake.

This was followed by a 32-day 'high-controlled fasting phase' where participants were given personalized meals, created by a dietitian, with a caloric value gradually decreasing to a quarter of their baseline energy intake.

Patients ate without restriction every other day and ate the restricted meals on the other days.

This was followed by a 30-day 'low-controlled fasting phase', during which they were given a list of recommended foods, but not the actual meals.

Female participants would receive compensation of 500 calories per day, while men received 600 calories.

The researchers noticed a decrease in the activity of brain areas involved in the regulation of appetite and addiction after both fasting phases. This may mean that people are hungrier.

Researchers saw increased activity in the brain regions for attention, emotion and learning, meaning people may be better at performing tasks that require these skills.

Researchers saw a sharp increase in the bacteria Faecalibacterium prausnitzii, Parabacteroides distasonis and Bacterokles uniformis in the intestinal microbiome.

Faecalibacterium prausnitzii increases the immune system's ability to fight inflammatory interactions, while P. distasonis is thought to help alleviate obesity and Bacterocles uniformis improves the intestinal barrier.

Meanwhile, E. coli bacteria decreased. The bacteria can help control appetite by releasing hormones that tell the brain that the body is full. With fewer E. coli bacteria, people may have less control over their appetite.

Participants also lost an average of 16.7 pounds during the study.

Dr. Li said: 'A healthy, balanced gut microbiome is critical for energy homeostasis and maintaining normal weight.

'An abnormal gut microbiome, on the other hand, can change our eating behavior by affecting certain brain areas involved in addiction.'

The research was published in the journal Frontiers in cellular and infection microbiology.