How an Intermittent Energy Restriction Diet May Help with Weight Loss

A woman drinks from a water bottle at an outdoor basketball court
Experts say staying hydrated is important when following a diet plan. Alexandr Muşuc/Getty Images
  • A new study has found that a diet known as Intermittent Energy Restriction (IER) not only aids weight loss but positively alters gut microbiome and brain activity. 
  • The results show that IER causes decreases in the activity of brain regions involved in the regulation of appetite and addiction.
  • It may also help with attention, motor inhibition, emotion, learning, and willpower.
  • However, experts say IER isn’t for everyone, particularly people with type 1 and 2 diabetes or a history of disordered eating. 

New research is reporting that losing weight via a diet known as intermittent energy restriction (IER) significantly alters gut microbiome and improves brain activity.

In turn, that may also help people’s weight loss efforts. 

In their study, researchers studied stool samples, blood measurements, and functional magnetic resonance imaging (fMRI) to determine how gut microbiome and brain activity changed in 25 Chinese men and women with obesity on an IER diet.

Participants were on average 27 years old with a body mass index (BMI) between 28 and 45.

Intermittent energy restriction involves alternating between periods of eating in a calorie deficit and periods of eating at maintenance calories.

During the study, participants underwent a high-controlled fasting phase for 32 days where they decreased their caloric intake by one-quarter of their basic energy intake. They then spent 30 days in a “low-controlled fasting phase.”

By the end of the study, the participants’ body weight had decreased by an average of 7.6 kilogram, or about 7.8%. The authors said they also observed decreases in the activity of brain regions involved in the regulation of appetite and addiction.

Meanwhile, in the gut, the abundance of the bacteria Faecalibacterium prausnitzii, Parabacteroides distasonis, and Bacterokles uniformis increased sharply, while Escherichia coli (E. coli) fell.

Why is that important? Researchers explained that the abundance of distasonis and Flavonifractor plautii were positively correlated with brain regions associated with attention, motor inhibition, emotion, and learning.

Meanwhile, E. coli, which decreased significantly, was negatively associated with brain regions known to play a key role in executive function, including the will to lose weight.

What experts think of intermittent energy restriction diet study

Reema Patel, a London-based dietitian at Dietitian Fit, said she isn’t surprised by the significant weight and body fat percentage reduction in this study.

Patel, who wasn’t involved in the study, says this is to be expected due to the level of caloric restriction. She added, however, that the diet’s impact on the gut and the brain is fascinating.

“What is interesting is the change in the abundance of specific types of gut bacteria with an increase in those that support the brain in learning and emotion and a decrease in certain bacteria that influence our will to lose weight,” Patel told Healthline.

“Although the mechanisms are not clear, it is surprising to see how much of an influence the restriction of food intake can have on certain activity in the brain,” she noted.

For Sas Parsad, a nutritionist and founder of The Gut Co, the results of this study align with the evolving understanding of the intricate relationship between the gut, the brain, and weight management.

“While not entirely surprising given the emerging body of research in this field, this study adds valuable insights into how lifestyle interventions, such as IER, can orchestrate synchronized changes across the brain-gut-microbiome axis,” Parsad, who was not involved in the study, told Healthline.

How IER alters gut microbiome and brain activity

You might be wondering why losing weight via IER seems to have this effect.

The first thing to know is that there is a bidirectional communication link between the gut and brain. This basically means that the gut and the brain are in constant two-way communication with one another.

Patel says just as the brain influences activities within the gut, the gut is also responsive to our mood and cognition.

When you fast, the body shifts from using glucose as a primary energy source to metabolizing stored fats. Parsad says this shift triggers a cascade of events, including changes in hormone levels and neurotransmitter activity alterations.

Meanwhile, the gut microbiome, sensitive to changes in dietary patterns, responds to fluctuating nutrient availability.

“The resulting metabolic changes in the gut influence the production of signaling molecules that can impact the brain,” Parsad explains.

“This bidirectional communication leads to adjustments in brain regions related to appetite regulation, motivation, and addiction, creating a synchronized response across the brain-gut-microbiome axis,” Parsad added.

One hormone in particular that may be affected is serotonin. Patel notes that it’s known to regulate appetite and promote good moods, though more research is needed.

Trying the intermittent energy restriction diet

If you want to try IER for yourself, how should you begin?

Parsad recommends starting gradually.

“Begin with shorter fasting periods and gradually extend them over time,” he suggests. “This helps the body adjust to the changes in nutrient availability.”

It’s important to choose nutrient-dense foods to ensure your body receives essential vitamin minerals, too. Parsad says you’ll want to include plenty of protein to support muscle health and satiety. Keeping hydrated is also key.

Most importantly, Parsad says you should listen to your body.

“Pay attention to hunger cues and adjust the duration and intensity of fasting periods based on individual comfort and tolerance,” he advises.

A word of warning though. Patel says there is a risk of developing nutrient deficiencies if your IER diet isn’t properly planned out, so it’s probably best to consult with a professional before you get started.

“Additionally, this style of eating may not work for those with certain medical conditions such as type 1 or 2 diabetes, especially where medication is required at certain times of the day with meals,” Patel noted.

She added that the diet should also be avoided by people with a history of disordered eating.

Takeaway

This new study shows that losing weight can also benefit the gut and the brain.

IER won’t be for everyone, but for some it can be an effective weight loss tool.

It can also have a positive impact on appetite regulation, willpower, and emotion.

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