A study published in Nature Communications has revealed that intermittent fasting and protein pacing leads to a more diverse gut microbiota compared to a calorie-restricted, heart-healthy diet.
This finding may have significant implications for understanding the relationship between gut microbiome and metabolism, potentially informing new strategies for managing obesity.
The gut microbiome, a complex community of microorganisms residing in the intestines, plays a crucial role in controlling body weight and overall health. Scientists know that nutrient availability can significantly influence this balance.
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While restricting calorie intake, intermittent fasting (limiting food consumption to certain windows on some days) and protein pacing (spreading your protein intake throughout the day, rather than in one meal) are known to impact body weight, their effects on gut microbiota have been less clear until now.
In this small trial, researchers compared two dietary interventions over eight weeks involving 41 overweight or obese individuals.
One group followed a Mediterranean-style, calorie-restricted diet based on US dietary guidelines, while the other group adhered to a calorie-restricted regimen that included intermittent fasting and protein pacing (known as the IF-P diet).
The results showed that individuals in the IF-P group experienced a greater diversity of gut microbiota, reduced gastrointestinal symptoms and a more substantial loss of visceral fat compared to the calorie-restricted group.
Notably, the IF-P diet increased certain gut microbes associated with a leaner body type and boosted circulating proteins and amino acids linked to weight loss and fat oxidation, respectively.
“While it is an interesting study, suggesting protein pacing and intermittent fasting help to support weight loss, as shown in a study published in 2023, in this analysis this appeared to be linked to improved gut bacteria levels,” said Dr Duane Mellor – dietitian and spokesperson for the British Dietetic Association, and honorary academic fellow at Aston University – who was not involved in the study.
Mellor pointed out that, as things stand, it’s unclear whether this is an effect of higher protein levels in the protein pacing and intermittent fasting diet, the effect of intermittent fasting itself, the higher levels of fibre in the diet or a combination of factors.
He added that the higher fibre content in the IF-P diet at least partly explains the observed differences in gastrointestinal health and gut microbiota.
While the study's diets were "carefully designed", Mellor emphasised the research's limitations, including its small size and the use of supplements provided by the study funder (supplement manufacturer Isagenix), making the diet challenging to replicate using readily available foods.
Despite these constraints, the findings could support further studies that examine the complex metabolic interactions between diet and the gut microbiome.
About the expert
Duane Mellor is an award-winning registered dietitian and science communicator (BDA Media Spokesperson of the Year 2021), who is a visiting academic for Aston Medical School. After initially working in the areas of clinical trials, Mellor’s current research interests focus on improving nutrition and health by working with communities to celebrate their heritage through food and help tackle barriers resulting from societal inequalities.
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