Explorations Into the Mechanism for INSTI-associated Weight Gain: a Focus on Energy Balance

Weight gain following antiretroviral therapy (ART) initiation occurs with all modern regimens. Recent real-world reports suggest that integrase strand transfer inhibitor (INSTI)-based ART may be associated with excess weight gain compared to other regimens. Weight gain appears to occur regardless of baseline weight, and is most pronounced among women and minorities, often those at highest risk of obesity-associated comorbidities. INSTI- and TAF-based regimens are now preferred regimens for most persons according to the Department of Health and Human Services ART-Treatment Guidelines. As a result, there is an urgent need to understand the underlying mechanisms for this weight gain. This study aims to understand the changes in energy balance that occur with changes in ART. Participants with HIV who have experienced \>10% weight gain on INSTI (bictegravir or dolutegravir-based therapy) will be switched to doravirine for 12 weeks, and then back to their prior INSTI regimen, allowing for assessment of changes in metabolic parameters with drug withdrawal and reintroduction (with no change to NRTI-backbone). Twenty-four hour energy balance will be measured on both regimens during a 24-hour stay using a whole room indirect calorimetry, with a standardized diet. Ultimately, the investigator's goal is to understand the mechanisms of weight gain so that future interventions can most effectively mitigate ART-associated weight changes.