Changes in Gut Bacteria Could Help Explain Success of Protein Pacing Diets

Intermittent fasting and protein pacing are two approaches to weight loss that have become increasingly popular in recent years, and new research suggests they could also contribute to a more diverse gut microbiome.

Previous studies have pointed to links between the bacteria in our gut and our tendency to put on weight. These latest findings give us more clues as to how our inner microbes might be managed to keep our bodies in shape.

The researchers behind this latest work (a study largely funded by nutrition supplement company Isagenix) say their findings will be useful for understanding how the gut microbiome adapts to changes in what and when we eat – which intermittent fasting and protein-pacing diets put limits on.

"To maintain a stable community and ecosystem, the gut microbiome must regulate its growth rate and diversity in response to nutrient availability and population density," Alex Mohr, a microbiome researcher at Arizona State University, and colleagues write in their published paper.

The study enrolled 41 overweight or obese volunteers, who ate either a healthy, calorie-restricted Mediterranean-style diet based on US dietary recommendations, or a combined intermittent fasting and protein-pacing (IF-P) diet for two months.

A protein-pacing diet involves controlling protein intake at specific meals, while intermittent fasting limits food consumption to certain times on some days. Compared to the calorie-restricted diet, the IF-P diet had about 250-300 more calories per non-fasting day, but included more protein by gram on those days.

At the end of eight weeks, stool samples showed those on the IF-P diet had a more diverse selection of microbiota compared to the other group. The effects varied by individual, but overall the IF-P diet group reported experiencing fewer gastrointestinal problems. They also shed more visceral fat, the body fat most relevant to metabolic health risks such as diabetes and heart disease.

What's more, those on the IF-P diet showed a number of biological shifts associated with losing weight: more of the gut bacteria found in leaner body types, such as Christensenellaceae, and more proteins and protein fragments linked to different aspects of weight loss.

"This novel work provides insight into the gut microbe and metabolomic profile of participants following an IF-P or calorie-restricted diet and highlights important differences in microbial assembly associated with weight loss and body composition responsiveness," the researchers write.

This study involved a relatively small number of participants, so trials with larger groups of people are needed to help validate the results, but it suggests that particular types of diet might help remodel the gut and help with weight control.

We know that obesity is a growing problem – with over a billion people worldwide now classed as obese – and that obesity leads to a range of other health issues, including an increased risk of cardiovascular problems and certain cancers.

Encouragingly, the increased gut microbe diversity seen in the IF-P group is associated with other health benefits besides weight loss, including better digestive health and a more resilient immune system – which is definitely worthy of future research.

"These findings shed light on the differential effects of intermittent fasting regimens, including intermittent fasting and protein pacing as a promising dietary intervention for obesity management and microbiotic and metabolic health," the team concludes.

The study has been published in Nature Communications.