This intensive longitudinal study investigates the day-to-day stability and natural fluctuations of the gut microbiome in healthy adults over a 15-day period. While the human gut microbiome is a complex ecosystem, its baseline stability in the absence of disease or medical intervention remains insufficiently characterized due to low sampling frequency in prior research. By recruiting healthy volunteers for continuous daily sampling, this study aims to map temporal community structures and evaluate the stability of core microbiota. Additionally, the research utilizes Continuous Glucose Monitoring (CGM) to explore the potential relationships between microbiome dynamics, daily dietary intake, and host glycemic stability.