Intermittent fasting, calorie restriction may diversify gut bacteria

Evan Walker
Evan Walker TheMediTary.Com |
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Intermittent fasting may improve the diversity of the gut microbiome. Design by MNT; Photography by R A V E N/Stocksy & STEVE GSCHMEISSNER/SCIENCE PHOTO LIBRARY/Getty Images.
  • Intermittent fasting and calorie reduction both benefit diversity in the microbiome.
  • Gut bacteria in the microbiome are important to a range of health-related processes in the body, and a lack of diversity is tied to more diseases.
  • There are several so-called blue zones in the world — one in the United States — areas with extremely high rates of people who live past the age of 100 years.

Intermittent fasting and calorie reduction are both effective methods of supporting all-important microbiome diversity. A new study from the University of Colorado’s medical school highlights how changes in the gut microbiome, brought about through dietary interventions, can influence gene regulation and overall health.

Both intermittent fasting and calorie-reduction diets positively affect the microbiome, the community of bacteria living in a person’s digestive system and throughout the body.

Participants in the study, all of whom had either overweight or obesity, were either instructed to fast for 3 non-consecutive days each week for a year or, alternately, to reduce their regular caloric intake by around 34% over the same period.

An earlier analysis found that the diversity of gut bacteria in individuals’ microbiomes was significantly improved, even at only 3 months into the year-long study. Improvements were seen for both groups — those who fasted and those who focused on reducing their daily calorie intake.

The analysis suggested that a person can improve the diversity of their microbiome and potentially their overall health using the weight-reduction strategy of their choice.

The new study reinforces the idea that changes in gut bacteria occur during weight loss. The researchers observed several associations between the abundance of microbes associated with metabolism and obesity and DNA methylation, a process by which gene regulation is altered, potentially impacting our health.

The study appears in Nutrients.

The researchers, following their Health">earlier analysis, had commented that the mechanism could be the benefits seen with changes in metabolism, weight loss, cardiometabolic factors, or even improvements in dietary patterns associated with the two arms of intervention.

Dr. Bedford suggested a simpler reason. “The microbiome is working full-time,” he said. So when you fast or eat less, “[y]ou’re resting it, allowing it to repopulate, just like sleep. That’s certainly one of the theories as to why you’re improving [diversity] with intermittent fasting, things of that sort.”

Nevertheless, Kirkpatrick cautioned that “[t]here is no one size fits all approach to diet, so each individual diet needs to be assessed with a health practitioner.”

In addition, she advised that “[p]regnant women, [those who are] breastfeeding, or someone struggling with a chronic condition should speak with their doctor or dietitian prior to altering their dietary pattern.“

The dietitian also expressed concern that fasting diets and calorie reduction could cause further harm to people with a history of disordered eating.

“Individuals with a history of eating disorders or current disordered eating should also not consider fasting or low-calorie approaches,” said Kirkpatrick.

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