Social media tools have been touted as an approach to bring more democratic communication to health care. We conducted a multi-site cross-sectional study among persons living with HIV (PLWH) to desrcibe technology use among PLWH in the US and the association between social media use and body-mass index (BMI). Our primary predictor variable was social media use. Our primary outcome was BMI measured through height and weight. Descriptive statistics were used to describe the demographic profiles of the study participants and linear regression models were used to analyze associations between the outcome and predictor variables controlling for demographic characteristics. Study participants (N = 606) across 6 study sites in the United States were predominately 50-74 years old (67%). Thirty-three percent of study participants had a normal weight (BMI 18.5-25), 33% were overweight (BMI 25-30), and 32% were obese (BMI > 30). Participants used several social media sites with Facebook (45.6%) predominating. Social media use was associated with higher BMI in study participants (p < .001) and this effect persisted, although not as strongly, when limiting the analysis to those who only those who used Facebook (p = .03). Further consideration of social factors that can be ameliorated to improve health outcomes is timely and needed.