**Background:** Studies have shown an increase in weight among people living with human immunodeficiency virus (PLWH) who have also initiated integrase strand transfer inhibitors (INSTI). However, limited data are available regarding comparison of these changes with other antiretroviral regimens. **Objective:** To assess differences in weight gain after initiating INSTI- versus protease inhibitor (PI)-based regimens among treatment-naïve PLWH overall, and among a subpopulation of females only. **Methods:** This retrospective, observational cohort study included data from the Optum® deidentified Electronic Health Record (EHR) database. Adult PLWH who initiated INSTI- or PI-based regimens between March 1, 2016 and June 30, 2018 (index date was the first INSTI or PI prescription in this period) with ≥12-month baseline and follow-up periods, ≥1 weight measure during each period, and no prior antiretroviral use were included. The last weight measure between 12 months pre- and 30 days post-index was defined as baseline weight; the last measure between the months 4 and 12 of follow-up was defined as post-weight. Weight change was reported as absolute change and proportion of patients with increased weight. Cohorts were balanced using propensity score (PS) matching. Multivariable models were used to compare outcomes of interest. **Results:** After matching, 1588 patients were included (794 per cohort). At baseline, 46% were
