AbstractObjectivesIntegrase strand transfer inhibitors (INSTIs) are commonplace in modern antiretroviral therapy (ART). Increased weight gain with their use is increasingly scrutinized. We evaluated weight changes in treatment‐naïve adults with HIV‐1 attending a UK centre who started regimens including raltegravir or dolutegravir.MethodsA retrospective cohort study of adults prescribed an INSTI between January 2015 and March 2020 were categorized as having started an ART regimen containing raltegravir, dolutegravir, a protease inhibitor or a nonnucleoside reverse transcriptase inhibitor. Individuals with one or more weight measurement ≤ 5 years both pre‐ and post‐ART initiation, who started a three‐drug regimen with ≥ 6 months duration and achieved virological suppression (< 50 copies/mL) within 6 months were included. A random effects model with linear slope pre‐ and post‐ART was used, adjusting for age, gender, ethnicity, ART regimen, backbone and year of initiation.ResultsThe cohort included 390 adults; 88.7% were male, 66.4% were of white ethnicity, their median age was 40 years, there was a median of six weight measurements, 2.2 years from diagnosis to ART initiation, 2.9 years from ART to the last weight measurement, and weight and body mass index at initiation were 75 kg and 24.1 kg/m² respectively. Of these, 254 (65%) started an INSTI. The average pre‐ART rate of weight gain was 0.44 kg/year [95% confidence interval (CI): 0.19–0.70], increasing to 0.88 kg/year (0.63–1.10, p = 0.04) after ART initiation. Our adjusted model found no evidence of an association between ART regimen and rate of weight gain.ConclusionsWeight increased in the cohort both pre‐ and post‐ART. We found no evidence of a higher rate of weight gain following ART initiation with an INSTI compared with other regimens.