 fasting has become increasingly popular for managing metabolic and inflammatory diseases. Despite the role that the gut microbiome plays in health and disease, little is known about how it responds to fasting when the external nutrient supply is reduced or suppressed. In this study, 15 healthy participants underwent a 10-day period of fasting according to the Butchinger Fasting Guidelines, which involves a daily energy intake of approximately 250 calories and an enema every two days. The participant's serum biochemistry confirmed the metabolic shift from carbohydrates to fatty acids and ketones. Their emotional and physical well-being were enhanced. Fecal 16S RNA gene-amplicon sequencing showed that fasting caused a decrease in the abundance of bacteria known to degrade dietary polysaccharides such as lachnospiracea and ruminocococciacea. This was accompanied by an increase in bacteroids and prochabacteria, escharicicoli and bolofila wardsworthia, known to use hoster. This article was authored by Robin Meenage, Francisca Grundler, Andreas Schwitz and others. We are article.tv, links in the description below.