Background: The gut microbiome is altered in people living with HIV (PLWH). While antiretroviral treatment (ART) is pivotal in restoring immune function in PLWH, several studies have identified an association between specific antiretrovirals, particularly integrase inhibitors (INSTI), and weight gain. In our study, we wanted to explore the differences in the oral and gut microbiota of PLWH under different ART regimens, and its correlation to Body Mass Index (BMI). Methods: Fecal samples were collected from PLWH (n=80) and healthy controls (HC, n=90). DNA was extracted for shotgun metagenomic sequencing on the Illumina Novaseq platform. The obtained raw reads were pre-processed (removal of host DNA and adapters trimming), and taxonomy analysis was performed to determine the microbial composition. Further, Humann3 will be used for functional analysis.