Introduction: according to the global report on drug use, the prevalence of people who use drugs (PWUD) and hence require treatment are estimated to be more than a quarter of a billion worldwide. Malnutrition is highly prevalent among PWUD and hyperphagia is also present in the early phases of treatment. Objective: this study aimed to assess the association between weight gain amongst PWUD currently undergoing treatment for recovery whether in the rehabilitation centers or the opioid substitution therapy (OST) program centers in Lebanon. Methods: this was a cross-sectional study, where demographics ...