Intermittent fasting promises improved gut health and weight control

A new study by Arizona State University researchers and their colleagues highlights dietary strategies for significantly improving health and weight control.

Participants who followed an intermittent fasting and protein diet, which involves consuming protein evenly throughout the day, showed better gut health, weight loss, and improved metabolic health. These benefits were significantly greater compared with simple caloric restriction.

The findings, published in Nature Communications, may expand our understanding of the link between the gut microbiome and metabolism, and improve strategies to combat obesity.

Researchers compared the effects of two low-calorie dietary interventions: a heart-healthy continuous calorie-restricted diet (based on USDA guidelines) and a calorie-restricted regimen that included intermittent fasting and protein food.

The trial was carried out on 41 overweight or obese people over eight weeks. Individuals in the intermittent fasting and protein group showed a reduction in symptoms of gastrointestinal problems and an increase in gut microbiota diversity compared to the calorie restriction group.

Intermittent fasting increased the number of beneficial microbes in the gut, which are associated with a lean physique and overall improved health. It also increased levels of certain proteins (cytokines) in the blood that are associated with weight loss, as well as amino acid waste products that promote fat burning.

Intermittent fasting is an eating pattern that alternates periods of fasting and eating. This method has recently become popular for its potential health benefits, including weight loss, improved metabolic health and improved brain function.

“Given the location of the gut microbiota and its ongoing interaction with the gastrointestinal tract, we have gained greater understanding in recent years of its key role in dietary responses,” says Alex Moher, lead author of the new study.

“Although the study is limited in time and sample size, this comprehensive study—which included analyzes of the gut microbiome, cytokines, fecal short-chain fatty acids, and blood metabolites—highlights the complex interplay between diet, host metabolism, and microbial communities.”

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Moher led microbiome and molecular studies assessing the composition of gut microbes, inflammatory molecules called cytokines, short-chain fatty acids (SCFAs) and the metabolome.

Moher is a researcher at the Center for Microbiome Health at Arizona State University. Center director Rosa Krajmalnik-Brown and researchers Devin Bowes, Karen Sveazeya and Corrie Wisner also contributed to the study.

Co-author Paul Anchiero of the Department of Health Sciences and Physiology at Skidmore College led the clinical trial that tracked weight loss and body composition.

The study also included contributions from Arizona State University researchers Paniz Jasbi and Judith Klein-Seetharman of the School of Molecular Sciences, and Dorothy Sears and Highway Gu of the College of Health Solutions.

Intermittent fasting has been shown to have a positive effect on the gut microbiome, promoting the growth of beneficial bacteria, which can improve the overall health of the digestive system. A new study shows the benefits of an intermittent fasting diet with protein for weight control.

Digestive system, microbiome and weight loss

The gut microbiome is a diverse community of microorganisms found in the gastrointestinal tract, including bacteria, viruses, fungi and other microbes. These complex ecosystems play an important role in vital body functions and overall health.

The gut microbiome helps break down food, produce vitamins, and promote nutrient absorption. It plays a role in the development and functioning of the immune system, protecting the body from harmful pathogens. Finally, the gut microbiome actively regulates metabolism, influencing body weight, fat storage, and insulin sensitivity.

Calorie restriction, intermittent fasting (limiting food intake to certain time windows) and protein feeding (controlled protein intake at certain meals) have shown effects on body weight and body composition, but the impact of these dietary changes on the gut microbiome is still unknown it was unclear.

The human gut contains trillions of bacteria and other microbes that together form the gut microbiome. New research is looking at how these diverse microorganisms help regulate weight. Researchers at Arizona State University are studying the effects of an intermittent fasting diet combined with protein distribution on body weight and overall health. Source: Arizona State University Biodesign Institute

“A healthy gut microbiome is essential for overall health, especially in the management of obesity and metabolic diseases,” says Sveazea, principal investigator at Arizona State University.

“Gut bacteria influence how we store fat, balance glucose levels and respond to hormones that make us feel hungry or full. Disturbances in the gut microbiota can lead to increased inflammation, insulin resistance and weight gain, highlighting the critical role of gut health in preventing and managing metabolic disorders."

Research and results

The clinical trial included 27 women and 14 men who were overweight or obese. Participants were divided into two groups: one followed an intermittent fasting and protein diet, and the other followed a heart-healthy, calorie-restricted diet. Both groups were followed for eight weeks to measure changes in body weight, body composition, gut microbiome composition, and plasma metabolic parameters.

Participants who followed an intermittent fasting and protein diet experienced a significant reduction in gut symptoms and an increase in beneficial bacteria in the gut, especially from the Christensenellaceae family. The study also found that these microbes are associated with improved fat oxidation and metabolic health. In contrast, the calorie restriction group showed an increase in metabolites associated with pathways associated with longevity.

Although both groups had similar average weekly energy intake, the intermittent fasting and protein group achieved greater weight loss and fat reduction, losing an average of 8.81% of their starting body weight over the course of the study. In comparison, those who followed the calorie-restricted diet lost an average of 5.4% of their body weight.

Participants following the intermittent fasting protein diet experienced a decrease in total body fat, including belly fat and deep abdominal fat, and an increase in the percentage of muscle mass.

Study highlights the potential of intermittent fasting and protein diets to improve gut health and weight control. Although further research is needed, these findings offer a promising path toward developing effective dietary interventions to combat obesity and related metabolic disorders.

“By identifying changes in specific microbes, functional pathways and associated metabolites, this line of research offers promise for personalized health strategies as we can better tailor dietary regimens to improve gut function and metabolic outcomes,” says Moher.